Answer:
Inventing gadgets to make their work easier.
Protecting the country using bombs and guns.
Explanation:
Yasir wants to determine if there is a relationship between room color and sleep. Based on his research, Yasir makes an educated guess that people fall asleep more quickly in a room painted blue than in a room painted yellow. He asks several people which color they like better—yellow or blue—and uses their responses to determine if his educated guess was correct. What is missing from Yasir's scientific investigation? A. testable hypothesis based on research B. experiment that tests the hypothesis C. variables to be tested by an experiment D. research on the topic to see what others have learned
Answer:
B). An Experiment that tests the hypothesis.
Explanation:
The element that is missing from Yasir's scientific investigation is 'an experiment which tests a hypothesis.' His experiment does not provide a verifiable statement revealing his proposition or prediction regarding the possible outcome of the experiment which could be verified by using a research or investigation. He rather tests his proposition indirectly by asking 'which color they like better' and using it to make an educated guess. Thus, option B is the correct answer.
Nitrogen dioxide undergoes thermal decomposition according to the second-order reaction 2 NO2(g) 2 NO(g) + O2(g). When 0.500 M NO2 is allowed to react for 90.0 seconds, its concentration falls to 0.0196 M. What is the half-life of the reaction when [NO2]0 = 0.500 M?
Answer:
half-life is 3.67s
Explanation:
The general law of the second-order reaction is:
[tex]\frac{1}{[A]}=\frac{1}{[A]_0}+kt[/tex]
As after 90.0s, the concentration of NO2 decreases from 0.500M to 0.0196M:
[tex]\frac{1}{[0.0196]}=\frac{1}{[0.500]}+k*90.0s[/tex]
49.02M⁻¹ = K*90.0s
0.5447M⁻¹s⁻¹ = K
Now, half-life, t1/2 is:
[tex]t_{1/2}=\frac{1}{K[A]_0}[/tex]
Half-life is:
t(1/2) = 1 / (0.5447M⁻¹s⁻¹*0.500M)
half-life is 3.67sHow many Significant Figures does 105.60 have? *
Answer:
5 significant figures
Explanation:
Suppose you are asked to determine whether a nugget is made of gold on the basis of its density. You weigh the nugget and find that it has a mass of 163 grams (g). Then you carefully add it to a graduated cylinder that contains 50.0 milliliters (mL) of water and observe that the water level in the cylinder rises to 58.5 mL. What is the density of the nugget in grams per cubic centimeter?
Answer:
Explanation:
density is mass over volume
Mass = 163 grams
Volume = 58.5 - 50.0 = 8.5
density = 163 / 8.5
density = 19.176
To 3 figures that 19.2 grams / mL
Answer:
density is mass over volume
Mass = 163 grams
Volume = 58.5 - 50.0 = 8.5
density = 163 / 8.5
density = 19.176
To 3 figures that 19.2 grams / mL
Explanation:
You have a stock solution that is 226mg/mL and you need 10mL of a working solution that is 15mg/mL. What is the volume of stock solution will you need to dilute to have 10mL of working solution at the above concentration. State your answer to two decimals.
Answer: 0.67 ml
Explanation:
According to the dilution law,
[tex]C_1V_1=C_2V_2[/tex]
where,
[tex]C_1[/tex] = concentration of stock solution = 226 mg/ml
[tex]V_1[/tex] = volume of stock solution = ?
[tex]C_2[/tex] = concentration of working solution= 15 mg/ml
[tex]V_2[/tex] = volume of working solution= 10 ml
Putting in the values we get:
[tex]226mg/ml\times V_1ml=15mg/ml\times 10ml[/tex]
[tex]V_1=0.67ml[/tex]
Thus volume of stock solution needed to dilute to have 10mL of working solution at the above concentration is 0.67 ml
Which kind of investigations never include a hypothesis?
O experimental
O systematic
O descriptive
O comparative
Answer:
the answer is descriptive
Explanation:
descriotive never ever have hypothisis
One half of a balanced chemical equation is shown. 3Mg(OH)2 + 2H3PO4
Answer:
3Mg(OH)2 + 2H3PO4 = Mg3(PO4)2 + 2H3O
Explanation:
Question:
Which lists the numbers of each atom the other half of the equation would contain?
Equation:
3Mg(OH)2 + 2H3PO4
Options:
3 Mg, 2 P, 14 O, 12 H Mg, 2 P, 14 O, 6 H 3 Mg, 8 P, 7 O, 6 H 6 Mg, 6 P, 2 O, 12 HAnswer:
A) 3 Mg, 2 P, 14 O, 12 H
Explanation:
I just did the test on edge 2020 and got the answer right. Also, my dog said hi.
Sand is made of tiny pieces of rock that have been worn down by wind and water. Explain why the formation of sand is a physical change.
Answer:
This change is only a physical change because the wind and water do not change the chemical make-up of the rock, the weathering is only changing the size nothing else.
Explanation:
Physical changes happen when objects or substances experience a change that does not alter their chemical constitution.
Because some of the physical characteristics of the rocks change, but their personalities do not. The shreds of rock are ordered as their sizes and shapes change, but their identities and total section endure the same.
9. How many significant figures are there in the number 0.0001372?
A) 7
B) 3
C) 8
D) 4
E) 0
Answer: D. 4
Explanation:
For numbers with decimal point, we should start counting from the first number that non-zero from the left.
0.0001372
We start counting from 1, since it is the first non-zero number
1, 3, 7, 2
There are in total 4 significant figures
Hope this helps!! :)
Please let me know if you have any question or need further explanation
You are unsure of the volume of a substance, but you know that it has a density of 4 g/ml and a mass of 16 grams. What is its volume?
Answer:
4 mL
Explanation:
Use the density formula, d = m/v
Plug in the density and mass to solve for v:
4 = 16/v
4v = 16
v = 4
So, the volume is 4 mL
Tessa knows that the sea grape tree can grow well in areas of high st and poor soil. She has seen sea grape growing along the beach strands and coastal hammocks of south Florida. She sets up an experiment to see which amount of salt is best for sea grape. She chooses two plants. She gives pure water to the first plant and a strong salt water solution could Tessa do to improve her experiment? the econd. Then, she measures growth.
Is it possible for an object to lose weight but at the same time not lose any
mass?
Answer: NO
Explanation:
When you lose weight, you lose mass. These to are directly linked together
Consider this: weight=mass×gravity
If weight decreases, mass also decreases basing on the expression. Gravity is constant (meaning it will not change because mass or weight changes) so it will not impact the result.
Hope this helps!! :)
Please let me know if you have any question
It is possible for an object to loose weight and not loose mass.
The weight of a body is obtained as W= mg where;
W = weight of the body
m = mass of the body
g = acceleration due to gravity
Since the magnitude of the weight of a body depends on its mass, and acceleration due to gravity it is possible for an object to loose weight and not loose mass.
The value of acceleration due to gravity is not the same at all points in the universe. Hence, if an object is moved to a location where the value of acceleration due to gravity is lower, the object will loose weight but not mass.
The mass of an object is constant and does not change irrespective of the location where it is measured.
Learn more: https://brainly.com/question/13860566
WORTH 60 POINTS DONT PLAGIARIZE OR WILL REPORT. thanks :) You and your family are going on a trip in Europe. Calculate the speed in the following picture. Show your work and include units. Include 4-5 sentences explaining.
Answer:80
Explanation:
It would be 80 kilometers an hour. All you have to do is divide the total distance traveled which in this case is 240 kilometers, by the number of hours driven which is 3 hours.
which best describes an element? - a pure substance - a type of a mixture - a pure compound - an impure substance
Answer:
A pure substance
Explanation:
An element is a pure substance.
It is only made up of atoms of the same type.
when a candle burns what form of energy does the chemical energy in the candle change
Explain how heat as a reactant or product in a chemical reaction makes the change endothermic or exothermic?
✅Chemical reactions often involve changes in energy due to the breaking and formation of bonds. Reactions in which energy is released are exothermic reactions, while those that take in heat energy are endothermic.
IamSugarBee
Answer:
Heat as a reactant makes the change endothermic, while heat as a product makes the change exothermic.
Explanation:
In an endothermic reaction, heat is a reactant, making the endothermic reaction cooler than its surroundings. This can be compared to how an ice cube melting requires heat as a reactant.
In an exothermic reaction, heat is a product, making the exothermic reaction hotter than its surroundings. This is compared to how a fire releases heat into the air as a product.
Given that the density of iron is 11.35 grams per centimeter
cubed, what would be the volume of a 1.1 gram piece of iron?
Answer:
Volume = 0.097 cm³Explanation:
Density of a substance can be found by using the formula
[tex]Density(\rho) = \frac{mass}{volume} [/tex]From the question
Density = 11.35 g/cm³
mass of iron = 1.1 g
To find the volume substitute the values into the above formula and solve for the volume
That's
Making volume the subject we have
[tex]volume = \frac{mass}{Density} [/tex]So we have
[tex]volume = \frac{1.1}{11.35} [/tex]= 0.096916
We have the final answer as
Volume = 0.097 cm³Hope this helps you
I would really appreciate help on this! Thank you.
Classify the following as a chemical or
physical property:
Chlorofluorocarbons destroy ozone.
Answer: Chemical
Explanation:
The reaction of destroying is a chemical change in the ozone molecules.
Which of the following describes the difference between Carbon−12 and Carbon−14? A. Carbon-12 has 12 electrons, 12 protons, and 12 neutrons; Carbon−14 has 14 electrons, 14 protons, and 14 neutrons. Both are radioactive isotopes. B. Carbon-12 has 6 electrons, 6 protons, and 6 neutrons; Carbon−14 has 6 electrons, 6 protons, and 8 neutrons. Both are radioactive isotopes. C. Carbon−12 has 6 electrons, 6 protons, and 6 neutrons; Carbon−14 has 6 electrons, 6 protons, and 8 neutrons. Only Carbon−14 is a radioactive isotope. D. Carbon−12 has 6 electrons, 6 protons, and 6 neutrons; Carbon−14 has 6 electrons, 6 protons, and 8 neutrons. They are not radioactive isotopes.
Answer:
B
Explanation:
How many centimeters are in 5.46 meters
Answer: 546 meters
Explanation: multiply the length value by 100
An element is defined in chemistry as
Answer:
In chemistry, an element is a pure substance which cannot be broken down by chemical means, consisting of atoms which have identical numbers of protons in their atomic nuclei. The number of protons in the nucleus is the defining property of an element,
A 210 gram piece of metal has a volume of 81 cm3. What is the density of this metal?
Question 15 options:
129 g/cm3
2.59 g/cm3
0.39 g/cm3
17,010 g/cm3
291 g/cm3
Answer:
The answer is
[tex]2.59 \: \: g / {cm}^{3} [/tex]Explanation:
The density of an object can be found by using the formula
[tex]Density( \rho) = \frac{mass}{volume} [/tex]From the question
mass of metal = 210 g
volume = 81 cm³
Substitute the values into the above formula and solve for the density
That's
[tex]Density = \frac{210}{81} \\ = \frac{70}{27} [/tex]= 2.592592
We have the final answer as
Density = 2.59 g/cm³Hope this helps you
Dimensional analysis, Plz hell I don’t understand and plz explain
Explanation:
30 lb is 480 ounces
34 mi/second is 54.718 kilometre/ second
455 lb/ gal is 54521.024 grams / litre
50 cl is 500 millilitres
55nm is 5.5 × 10^-6 centimetre
What is the weight of 2.5 ml of a solution that has a density of 1 g/mL?
Answer:
Density=mass / volume.
1= mass × 2.5.
mass = 2.5×1.
mass=2.5g
Carlos has 1.2 m a long piece of wood? how long is this in millimeters
Answer:
1200 millimeters
Explanation:
if there are 1000 millimeters in a meter then you have to multiply 1.2 meters by 1000 to get the number of millimeters. 1.2*1000=1200mm
3.490 x 10^-3 + 1.100 x 10^-2 in scientific notation
Answer:36
Explanation:
SOLVE Use the density formula to solve the following problems. A sample of a substance has a volume of 60.5 mL and a density of 1.20 g/mL. What is the mass of the sample?
The mass of the sample is 72.6 g. when a sample has a volume of 60.5 mL and a density of 1.20 g/mL.
What is the density?Density may be defined as the physical property of any object. It may be characterized as the measurement of quantity or mass per unit of volume in a particular substance.
According to the question, the volume of a sample = 60.5 mL.
The density of a sample = 1.20 g/mL.
Now, the formula for density is as follows:
Density = Mass/Volume.
But we have to calculate the mass of the sample, so the modified formula is = Mass = Density x Volume.
∴ Mass = 1.20 g/mL x 60.5 mL = 72.6 g.
Therefore, the mass of the sample is 72.6 g. when a sample has a volume of 60.5 mL and a density of 1.20 g/mL.
To learn more about Density, refer to the link:
https://brainly.com/question/1354972
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I need help will give you fives star
Answer:
2
Explanation:
The maximum amount of electrons in an atom that can share those quantum numbers because of the spin quantum numbers (ms) +1/2 and -1/2.
please solve this problem
Answer:
option D is correct
Explanation:
the molecule of nitrogen and ethyne have triple bond in them
N2= N≡N
ethyne =CH≡CH
what is conditional reflexes??
Answer:
Actions that you have trained yourself to perform.
they are obtained by experience. they are not passed from generation. they can be learnt or abolished. Higher center's of brain is responsible for conditional reflexes
Explanation:
example riding a bike, swimming, typing