Complete Question:
In ∆ABC, if sin A = 4/5 and tan A = 4/3, then what is cos A?
Answer:
[tex]cos A= \frac{3}{5}[/tex]
Explanation:
Given
[tex]sin A = 4/5[/tex]
[tex]tan A = 4/3[/tex]
Required
[tex]cos A[/tex]
In trigonometry;
[tex]tanA = \frac{sinA}{cosA}[/tex]
Multiply both sides by cosA
[tex]cos A * tanA = \frac{sinA}{cosA} * cos A[/tex]
[tex]cos A * tanA = sinA[/tex]
Divide both sides by tanA
[tex]\frac{cos A * tanA}{tanA} = \frac{sinA}{tanA}[/tex]
[tex]cos A= \frac{sinA}{tanA}[/tex]
Substitute values for sinA and tanA
[tex]cos A= \frac{4/5}{4/3}[/tex]
[tex]cos A= \frac{4}{5} / \frac{4}{3}[/tex]
[tex]cos A= \frac{4}{5} * \frac{3}{4}[/tex]
[tex]cos A= \frac{4 * 3}{5 * 4}[/tex]
[tex]cos A= \frac{3}{5}[/tex]
Consider the reaction of 2.5 grams of Li (s) reacting with 0.5 grams of N2 (g) to produce Li3N (s). A) How many total grams of Li3 N (s) would be produced? B) Which of the starting elements is the limiting reagent, and how many grams of the non-limiting reagent remain after the reaction has completed?
Answer:
A) The amount in grams of Li₃N produced is 1.243 g
B) N₂, is the limiting reagent
The mass of the non-limiting reagent, Li, remaining after the reaction is completed is 1.757 g
Explanation:
The given parameters are;
The mass of Li(s) = 2.5 grams
The mass of N₂ (g) = 0.5 grams
The chemical equation for the reaction can be presented as follows;
6 Li (s) + N₂ (g) → 2 Li₃N
Therefore, 6 moles of Li reacts with 1 mole of N₂ to produce 2 moles of Li₃N
The molar mass of Li = 6.941 g/mol
The molar mass of N₂ = 28.0134 g/mol
The number of moles of a reactant or product, n is given by the relation;
n = Mass of substance/(Molar mass of the substance)
For lithium, Li, n = 2.5/6.941 = 0.3602 moles
For Nitrogen gas, N₂, n = 0.5/28.0134 = 0.01785 moles
A) Given that 1 mole of N₂ to produces 2 moles of Li₃N
0.01785 moles of N₂ will produces 2×0.01785 = 0.0357 moles of Li₃N
The molar mass of Li₃N = 34.83 g/mol
The mass of Li₃N = 34.83 g/mol × 0.0357 moles = 1.243 g
B) 6 moles of Li reacts with 1 mole of N₂ to produce 2 moles of Li₃N
0.3602 moles will reacts with 1/6×0.3602 = 0.06003 mole of N₂
Therefore, N₂, is the limiting reagent and we have;
0.01785 moles of N₂ will react with 6×0.01785 = 0.1071 moles of Li
The number of of moles of Li left = 0.3602 - 0.1071 =0.2531 moles
The mass of lithium left = 0.2531 moles × 6.941 g/mol = 1.757 g
The mass of lithium remaining after the reaction is completed = 1.757 g.
Explain the bonding that occurs between sodium and chlorine. Specifically, what kind of bonding takes
place, what’s the name of the resulting compound, and what properties would you expect this compound to
have with respect to water?
Answer:
About bonding
Explanation:
A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bond.
Answer:
An ionic bond occurs between sodium and chlorine where sodium has one electron while chlorine has seven electrons. The electron from sodium is lost and transferred to a chlorine atom which results in a sodium ion with a charge of one+ and a chloride ion with a charge of one-. These oppositely charged ions attract each other making a balanced charge to make a compound that is electrically neutral.. Sodium cation (Na+) and chlorine anion (Cl-) are attracted to each another to form sodium chloride (table salt). When dissolved in water, the sodium and chloride ions are strongly attracted to the polar water molecules because of ion-dipole interactions.
Explanation:
Think of a real life simple problem and apply scientific method to solve the problem given to the guide questions.
Scientific Approach is to identify a problem and finding solution to the problem. There are various steps in scientific approach to solve a problem,
Identify the problem
Analyze the impact
Find available solution
Evaluate different alternative solutions
Choose the best alternative
Apply the solution to the problem
Measure the results
Lets say there is a fire at some place.
There are various solution available, the fire can be slowed down by water, using fire extinguisher or sand.
The best alternative is to use fire extinguisher.
The fire is vanished after the use of fire extinguisher.
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What are differences between viruses and bacteria?
Answer:
viruses are computer program that replicate itself and distribute itself to another computer but bacteria is micro organism that contaminate our food and can make us sick
List the metals Mg, Cu, Au, Na and Al in the decreasing order of their reactivity with air.
Answer:
Na is most reactiveAlcuAu is less reactiveIN HEREAnswer:
Potassium (K)
Sodium (Na)
Calcium (Ca)
Magnesium (Mg)
Aluminium (Al)
Iron (Fe)
Lead (Pb)
Copper (Cu)
Silver (Ag)
Gold (Au)
Calculate the number of molecules present in 2.50 mol H2S?
A. 1.51 x 10^24 molecules
B. 2.50 x 10^23 molecules
C. 1.5 x 10^23 molecules
One mole of H₂S gas contains 6.022 × 10²³ H₂S molecules. Hence, 2.50 mol of H₂S contains 1.50 × 10²⁴ molecules. Thus, option A is correct.
What is Avogadro number?Any substance containing 6.022 × 10²³ number of atoms is called one mole of that substance. This number is called Avogadro number. Thus, one mole every elements contains Avogadro number of atoms.
Similarly a compound is made of molecules. One mole of a compound contains 6.022 × 10²³ number of molecules. The mass of a compound with Avogadro number of molecules is called its molar mass.
As any other compound, one mole of H₂S contains 6.022 × 10²³ molecules. Therefore, the number of molecules in 2.50 moles of H₂S is :
2.50 moles × 6.022 × 10²³ molecules/mol = 1.50 × 10²⁴molecules
Hence, the number of molecules present in 2.50 moles of H₂S is 1.50 × 10²⁴.
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urgent plz help thanks!
Which statement best describes a compound formed by an ionic bond?
A) negatively charged
B) neutral
C) contains multiple charges
D) positively charged
Answer:
B. Neutral
Explanation:
When there is a ionic bond, one element steals or takes away an electron from the other element.
An example is NaCl
In this compound, Chlorine atom steals an extra electron from Sodium to fill its outer shell. So, this is a Ionic bond. Since, the Sodium compound gives away an atom, it is positively charged. Since, Chlorine steals an atom, it is negatively charged. Opposite charges attract, so they become a compound.
When positive and negative mix, it becomes neutral.
what are the efficient things needed for a village
Answer:
Those aspects which are something a village needs are specified beneath.
Explanation:
Things being equally necessary to make living simpler and therefore more enjoyable. The government has promised to continue providing basic facilities to either an unpopulated location, including such roads, drinkable water, as well as electric power. Therefore, throughout the village, certain things accessible with maximum variety and quality that have become the basic requirements for this human existence.What are the requirements of any hypothesis in science?
Answer:
A scientific hypothesis must meet 2 requirements:
Explanation:
A scientific hypothesis must be testable, and;
A scientific hypothesis must be falsifiable.
Please help, this assignment is to hard for me. :(
Answer:
603000 J
Explanation:
The following data were obtained from the question:
Energy required (Q) =...?
Mass (M) = 10000 g
Specific heat capacity (C) = 2.01 J/g°C
Overheating temperature (T2) = 121°C
Working temperature (T1) = 91°C
Change in temperature (ΔT) =.?
Change in temperature (ΔT) =T2 – T1
Change in temperature (ΔT) = 121 – 91
Change in temperature (ΔT) = 30°C
Finally, we shall determine the energe required to overheat the car as follow:
Q = MCΔT
Q = 10000 × 2.01 × 30
Q = 603000 J
Therefore, 603000 J of energy is required to overheat the car.
In the figure a cyclist moves A to B and then to C.he could also go through the shortest path AC. Depending on this fact solve the following questions: Find the length of AC .Find the displacement and total distance covered.
Answer:
hope it helps you see the attachment for further information
What is conservation area write in 8 points
Answer:
The Conservation area is the pay way to the special architectural and historic interest these are special character.
Explanation:
Conservation area is the features of building and use that historical development to contribute to its special character material and style.
Conservation area is that contain process to the application management development process and local residents.Conservation is that the produce demolition of a building structure with the conservation area,contribute to the group in individually.Conservation area that are special protection in the trees to the dangerous tree and some of the fruit trees.Conservation area are often to the protected by their building, planning works, these character area of appearance.Development rights to the conservation area require to the planning and permission to the outside area.Conservation area is classified to the regulation and the restricted area to the department planning.Conservation area is a composed to the impact of materials and building and the setting of impact.The new development in the conservation area is to the process of the renewal and the managed in the conservation area.Which of the following describes the entropy change as a solution is made
from a liquid and solid?
O A. AS = 0
O B. ASAH
C. AS< 0
D. AS> 0
Answer:
S>O.
Explanation:
Chemical changes can reduced entropy in an open system. When gas turns into a liquid or when a liquid turns into a solid; entropy is reduced. hope this helps you :)
6. What type of bond is called covalent bond?
Answer:
ECovalent bond, in chemistry, the interatomic linkage that results from the sharing of an electron pair between two atoms. The binding arises from the electrostatic attraction of their nuclei for the same electrons. ... Silicon, carbon, germanium, and a few other elements form covalently bonded solids.
Please make me Brain liest );
what is local unit?
.
Answer:
Explanation:
Local unit means a county, city, village, or township.
A student with a body temperature of 37°C holds a piece of ice that has a
temperature of -8°C.
Which statement best explains what happens?
1. Thermal energy transfers coldness from the student's hand to the ice.
2. Heat transfers coldness from the ice to the student's hand.
3. Heat transfers thermal energy from the student's hand to the ice.
4. Thermal energy transfers heat from the student's hand to the ice.
Answer:
Thermal energy transfers hear from the students hand to the ice
A mixture of reactants and products for the reaction shown below is at
equilibrium in a 2.0 L container. What would most likely happen to the
equilibrium if the volume of the container were increased to 4.0 L?
N.(g) + 3H2(g)
22NH3(g)
Answer:
The system will shift to the left producing more moles of gases trying to maintain the original pressure of the system
Explanation:
Based on LeChatelier's principle, a change in temperature, pressure, volume or concentration on a system result in an opposing change trying to maintain the initial equilibrium conditions.
In the reaction:
N₂(g) + 3H₂(g) ⇄ 2NH₃(g)
4 moles of gas reacts producing 2 moles of gas.
In a gas reaction, the system will try to maintain the total pressure.
If the volume of the container increases, the system will shift to the side of the reaction that has more moles of gases in order to maintain the pressure.
That means if in the reaction the volume of the container increase from 2.0L to 4.0L the system will shift to the left producing more moles of gases trying to maintain the original pressure of the system.
Suppose you were given a substance and asked
to determine whether or not it was a plasma. Write
the characteristics you would look for to identify
the substance.
Answer:Particles in plasmas collide more often.
Plasma particles have high kinetic energy (they move quickly).
Plasma particles are far apart.
The ionized particles have no fixed volume
Explanation:
Plasma is the fourth form of matter which has freely moving electrons in it. The substance can be identified as plasma if its particles collide often and are far apart.
What is plasma?Plasma is a type of matter other than solids, liquids, and gas. They have similar properties to that of gas. Plasma particle collides are often like gases as they move freely in space. Like gases that have no definite shape and volume.
The plasma particles have ionic charges, positive and negative resulting in high kinetic energy. This property allows them to show electromagnetism and electrical conductivity.
The ionized particles are due to the high temperature that allows them to have the property of electrical conductivity and compression.
Therefore, the particles of plasma are ionized and have high kinetic energy.
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The element phosporus is located to the right of the element magnesium along the same period in the periodic table.
How old is a bone if it presently contains 0.3125g of C-14, but it was estimated to have originally contained 80.000g of C-14?
Half-life of C-14 is 5730 years
The age of the bone is the time taken to decay carbon -14 from a mass of 80 g to 0.3125 g. The decay time is 46209 years. That is the age of the bone.
What is carbon dating?Carbon -14 isotope is radioactive and undergoes nuclear decay by the emission of charged particles. The age of a fossil sample which contains carbon -14 can be determined using the time of decay.
Half life of C-14 = 5730 years
decay constant k = 0.693 / 5730 = 0.00012 yr⁻¹
Initial amount of C-14 = 80 g
final amount = 0.3125 g
Then the time taken to decay 80 g to 0.3125 g is t = 1/k ln (80/0.312)
t = ln (80/0.312) / (0.00012 yr⁻¹)
= 46209 years.
Therefore, the age of the bone is 46209 years.
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A mixture of gasoline and air explodes when it encounters a spark. This is
known as
O A. a synthesis reaction
O O O
B. a precipitation reaction
C. fuel efficiency
o
D. a combustion reaction
SUBMI
Answer:
D. A combustion reaction
Explanation:
Balance the equation: "Sodium oxide reacts with water to form sodium hydroxide and hydrogen." I can't find the correct coefficients to balance the equation. I have written my unbalanced equation in the file attached.
Answer:
So, sodium oxide + water = sodium hydroxide + hydrogen is written Na2O+H2O-->NaOH+H.
To balance the equation it should read NaO+H2O-->2NaOH
Explanation:
Na2O+H2O-->2NaOH+0H2.......the 0H2 is dropped because there is no value
The correct balance of equation will be
Na2O + H2O - - > 2NaOH
What is a balanced chemical equation?A chemical equation where the number of atoms on both the reactant side and the product side of the reaction are equal is called a balanced chemical equation.
In a balanced chemical equation, not only the number of atoms but the charge and the mass is the same on both sides of the equation.
A chemical equation needs to be balanced to validate the law of conservation of mass. The law of conservation of mass states that the 'mass can neither be created nor destroyed in a chemical reaction'.
If the chemical equation is not balanced, it will go against the fundamental law of law of conservation of mass.
Thus, the chemical equations need to be balanced.
Therefore to balanced the given chemical equation, we equate the number of atoms on both the reactant and the product side of the reaction.
It will be written as
Na2O + H2O - - > 2NaOH
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500kg, 42m, 675g, and 10m/s are all examples of what typed of data?b
500kg, 42m, 675g, and 10m/s are all examples of a: continuous data.
A numerical data can be defined as a data set that is expressed in numbers only or a data set consisting of numbers rather than words. A numerical data is also known as a quantitative data.
Generally, numerical data are classified into two (2) main categories and these are;
Discrete data: a discrete data is a data set in which the number of possible values are either finite or countable. Some examples are; the value of a fair die, number of pen in a box, number of eggs in a crate, etc.Continuous data: a continuous data is a data set that has infinitely many possible values and as such those values cannot be counted, which simply means they are uncountable. Any data (quantity) such as mass, height, volume, weight, density, velocity, length, pressure, temperature, speed, distance, time are generally classified as continuous data.In conclusion, mass (500 kg), height (42m), mass (675g), and speed (10m/s) are all examples of a: continuous data.
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A compound that has a sea of delocalized electrons has what type of bonding?
Answer:
Metallic Bonding
Explanation:
Metallic Bonding
In metallic bonds, the valence electrons from the s and p orbitals of the interacting metal atoms delocalize. That is to say, instead of orbiting their respective metal atoms, they form a “sea” of electrons that surrounds the positively charged atomic nuclei of the interacting metal ions.
How much does 9.8 liters of ammonia (NH3) weigh at standard temperature and pressure (273 K and 100 kPa)?
A. 13.84 grams
B. 7.44 grams
C. 17 grams
D. 12.91 grams
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Explain the reaction that would occur in a galvanic cell between solutions of Al 3+and Pb 2+ . Identify the oxidation and reduction reactions and the location of each reaction. Then, use the standard reduction potential tables to determine the cell potential.
Answer:
Al ==> Al^3+ + 3e
Pb^2+ + 2e ==> Pb
Oxidation is the loss of electrons. Reduction is the gain of electrons. Which half rxn above lost and which gained?
For the potential of the cell, look up the reductions potentials, change the sign of the Al half cell, add in the potential for the Pb and add them.
Explanation:
The diameter of neutral atoms generally decreases going left to right across one period on the periodic table. What change causes this decrease in diameter of atoms?
Explanation:
Atomic size gradually decreases from left to right across the periodic table because within a period of elements, all electrons are added to the same shell. However, at the same time, protons are being added to the nucleus, making it more positively charged. The effect of increasing proton number is greater than that of the increasing electron number. Therefore, there is a stronger nuclear attraction. This means that the nucleus attracts the electrons more strongly, pulling the atom's electron shells closer to the nucleus. As a result, the atomic diameter of the atom decreases.
How does the useable atoms of elements attain stability? Illustrate your answer with two example.
Answer:
An element which does not have two or eight electrons in its valence shell is unstable. It get stability by losing, gaining or sharing electron to complete noble gas electronic configuration. ... Elements attain stability by completing duplet or octet.
what does porous mean
Answer:
porous = allowing liquid or air to pass through slowly
I hope it's helpful
Answer:
It is a rock or or other materials, having minutes interstices through which liquid or air may pass.
Give the relation of energy (E) and frequency (v) as given by Planck. Calculate the frequency and energy of a photon of radiation having wavelength 3000°A.
Pls answer correctly,need it urgently...
Solution:-1
[tex]\\ \sf\longmapsto E=hv[/tex]
E denotes to Energy h denotes to planks constantv denotes to frequency.Solution:-2
Wavelength=3000Å[tex]\boxed{\sf \lambda=\dfrac{c}{v}}[/tex]
[tex]\\ \sf\longmapsto v=\dfrac{c}{\lambda}[/tex]
[tex]\\ \sf\longmapsto v=\dfrac{3\times 10^8m/s}{3000\times 10^{-10}m}[/tex]
[tex]\\ \sf\longmapsto v=0.001\times 10^{18}s^{-1}[/tex]
[tex]\\ \sf\longmapsto v=1.0\times 10^{15}s^{-1}[/tex]
Now
[tex]\\ \sf\longmapsto E=hv[/tex]
[tex]\\ \sf\longmapsto E=6.626\times 10^{-34}Js\times 1.0\times 10^{15}s^{-1}[/tex]
[tex]\\ \sf\longmapsto E=6.6\times 10^{-19}J[/tex]