Explain the concept of significant figures and why it is important in scientific experiments.​

Answer:

a) HCN and NaCN

Explanation:

Buffer solution is made by mixing either a weak base and its salt like ammonia and ammonium chloride or weak acid and its salt like HCN and its salt NaCN or acetic acid and sodium acetate .

In the given option , all of the rest of option has either strong acid or strong base or both  . In the last option both are salt so it can not form buffer solution .

It is capable of keeping the pH of the solution constant .

Answer:

Black

Explanation:

Answer:

Explanation:

The density of carbon tetrachloride can be found by using the formula

From the question

Volume = 225 mL

To find the mass of carbon tetrachloride in the flask subtract the mass of the flask from the total mass of the flask and carbon tetrachloride

That's

mass of carbon tetrachloride =

703.55 - 345.8

= 357.75 g

Substitute the values into the above formula and solve for the density

That's

We have the final answer as.

Density = 1.59 g/mL

Hope this helps you

Answer:

6. (2.7*[tex]10^{5}[/tex])

8. (1.0*[tex]10^{4}[/tex])

Explanation:

Answer:

Nothing has full knowledge of the world.

Senses can deceive us - science only provides us with an incomplete picture of the world.

Scientists can never be completely unbiased.

Science isn't free from error.

No way of knowing what is real - some things could be illusions

Explanation:

Answer:

Kindly check explanation

Explanation:

pm = picometer

Radius of platinum atom = 139 pm

1 pm = 1 × 10^-12 m

Hence,

139 pm = 139 × 10^-12 m

1 pm = 1 × 10^-10 cm

Hence,

139 pm = 139 × 10^-10 cm

B) mass of a single platinum atom = 3.24 × 10²² g

To obtain the diameter of 1 platinum atom in cm:

139 × 10^-10 cm

Number of atoms required :

48.1 cm / 1.39 × 10^-8 cm = 34.60 × 10^8 atoms

Mass in gram of P(t) :

(3.24 × 10²²) × (34.60 × 10^8) = 112.117 × 10^(22+8)

= 112.12 × 10^30 g

C) density (d) = 21.4 g/cm^3, diameter = 1.50 mm

V = πr^2h

h = 48.1cm ; r = 1.5 / 2 = 0.75 mm = 0.075cm

Density = mass / volume

Volume = π * 0.075^2 * 48.1 = 0.8499971cm³

Mass = density × volume

Mass = 21.4g/cm³ × 0.8499971cm³

= 18.19g

Answer:

A. The neutral-charged neutrons and positive-charged protons are found within the nucleus, and the negative-charged electrons orbit outside the nucleus of the atom.

Explanation:

An atom basically consists of three sub atomic particles. They are; Neutrons, Electrons and Protons.

The Electrons are negatively charged and can be found outside the nucleus of the atom,

The Protons are positively charged and can be found in the nucleus of an atom.

The Neutrons are neutral in terms of charged and can be found in the nucleus along with the protons.

The option that is correct is;

A. The neutral-charged neutrons and positive-charged protons are found within the nucleus, and the negative-charged electrons orbit outside the nucleus of the atom.

Answer:

lower than the separate atoms. Because an electron in this molecular orbital is strongly attracted to both nuclei, the electron is more stable (at lower energy) than it is in the 1s orbital of the hydrogen atom. Because it concentrates electron density between the nuclei, the bonding molecular orbital holds the atoms together in a covalent bond.

Answer:

0.719M AgNO₃

Explanation:

Based on the reaction:

MgBr₂ + 2AgNO₃ ⇄ 2AgBr + Mg(NO₃)₂

1 mole of magnesium bromide reacts completely with 2 moles of AgNO₃

To find molarity of AgNO₃ solution we need to determine moles of AgNO₃ and, as molarity is the ratio of moles over liter (13.9mL = 0.0139L). Now, to determine moles of AgNO₃ we need to use the reaction, thus:

Moles AgNO₃:

Moles of MgBr₂ are:

50.0mL = 0.050L * (0.100mol / L) = 0.00500 moles of MgBr₂.

As the silver nitrate reacts completely and 2 moles of AgNO₃ reacts per mole of MgBr₂:

0.00500 moles MgBr₂ * (2 moles AgNO₃ / 1 mole MgBr₂) =

0.0100 moles of AgNO₃ are in the solution.

And molarity is:

0.0100 moles AgNO₃ / 0.0139L =

Answer:

H2O- Hydrogen bonding, dipole dipole, and dispersion

CH4- Dispersion only

CO- Dispersion only

CH2Cl- Dipole dipole and dispersion only

Explanation:

Dipole- dipole interactions exist only in molecules that have a dipole moment such as water and dichloromethane. Water experiences intermolecular hydrogen bonding in addition to dipole-dipole interaction and dispersion forces due to the O-H bond in the molecule.

Nonpolar compounds only have dispersion forces acting between its molecules.

Explanation:

Find out more information about dispersion here:

https://brainly.com/question/3224009

Answer:

Be the anode

Explanation:

The standard hydrogen electrode is regarded as the standard reference electrode and it has been assigned an electrode potential of 0.0V.

If any substance has an electrode potential that is more negative than hydrogen, then that half cell will function as the anode when connected to the standard hydrogen electrode.

Similarly, any substance that has a more positive electrode potential than hydrogen will serve as the cathode when its half cell is connected to the standard hydrogen electrode.

Answer:

Fractional distillation and HP-LC

Explanation:

This is a technique useful for analytes with close boiling points. Any alcohol-ester azotopes can be further refined using high-performance liquid chromatography (HP-LC) column.

Answer:

read and green

Explanation:

By convention, the three primary colors in additive mixing are red, green, and blue. In the absence of light of any color, the result is black. If all three primary colors of light are mixed in equal proportions, the result is neutral (gray or white). When the red and green lights mix, the result is yellow.

Answer:

ground tumeric

Explanation:

Mix 1/4 cup water and 1/2 teaspoon of ground tumeric

Answer:

This question is incomplete. There is no highlight in red bolded text in the question but the answer to both the independent and dependent variables will be provided and explained in details.

Independent variable: decrease in temperature

Dependent variable: lifespan of battery

Explanation:

The independent variable of an experiment refers to the variable that is changed or manipulated by the experimenter in order to bring about an outcome. In this experiment, the DECREASE IN TEMPERATURE is the independent variable because it is what is being changed to effect a response in the battery lifespan.

On the contrary, the dependent variable is the variable that responds to the manipulation of the independent variable. In other words, the dependent variable is the outcome. In this experiment, the LIFESPAN OF THE BATTERY is the dependent variable because it is what is responding to the changes made by decreasing the temperature (independent variable)

Answer:

0.306 g/L

Explanation:

D = M/V

D= 3.45 g/11.24 L

D= 0.306 g/L

Answer:

The daughter nuclides of these two decay processes are [tex]^{192}_{78}Pt [/tex] and [tex]^{192}_{76}Os[/tex].

Explanation:

The beta emission is represented by:

A = (Z + 1) + (n - 1) = is invariant

n: neutron

p: proton

[tex]^{A}_{Z}X \rightarrow ^{A}_{Z+1}Y[/tex]

Hence, the daughter nuclide of the beta emission of Ir-192 is:

[tex]^{192}_{77}Ir \rightarrow ^{192}_{78}Pt[/tex]      

Now, electron capture is represented by:

A = (Z - 1) + (n + 1) = is invariant

[tex]^{A}_{Z}X \rightarrow ^{A}_{Z-1}Y[/tex]

Then, the daughter nuclide of the electron capture of Ir-192 is:

[tex]^{192}_{77}Ir \rightarrow ^{192}_{76}Os[/tex]    

Therefore, the daughter nuclides of these two decay processes are [tex]^{192}_{78}Pt [/tex] and [tex]^{192}_{76}Os[/tex].

I hope it helps you!

Answer:

pH = 12.35

Explanation:

The HCl reacts with NaOH, thus:

HCl + NaOH → NaCl + H₂O

1 mole of HCl reacts per mole of NaOH

To know the pH we must know the moles of NaOH and the moles of HCl that reacts

Moles NaOH and HCl

NaOH: 0.0280L * (0.230mol / L) = 6.44x10⁻³ moles

HCl: 0.0230L * (0.230mol / L) = 5.29x10⁻³

As moles NaOH > Moles HCl, the moles that remains of NaOH are:

Moles NaOH = 6.44x10⁻³ - 5.29x10⁻³ = 1.15x10⁻³ moles NaOH = Moles OH⁻

In 23.0mL + 28.0mL = 51.0mL = 0.0510L:

1.15x10⁻³ moles OH⁻ / 0.0510L =

0.0225M OH⁻

pOH = -log [OH⁻]

pOH = 1.647

And pH = 14 - pOH

Answer:

Dual nature of matter is an important concept in JEE physics and is basically the study of different nature that a matter possesses or exhibits. ... Hence, the matter is said to possess dual nature, i.e., it has both the properties of a particle and as well as a wave.

Answer:

1) The order of the reaction is of FIRST ORDER

2)   Rate constant k = 5.667 × 10 ⁻⁴

Explanation:

From the given information:

The composition of a liquid-phase reaction 2A - B was monitored spectrophotometrically.

liquid-phase reaction 2A - B signifies that the reaction is of FIRST ORDER where the rate of this reaction is directly proportional to the concentration of A.

The following data was obtained:

t/min                    0         10         20          30             40          ∞

conc B/(mol/L)    0       0.089    0.153     0.200       0.230    0.312

For  a first order reaction:

[tex]K = \dfrac{1}{t} \ In ( \dfrac{C_{\infty} - C_o}{C_{\infty} - C_t})[/tex]

where :

K = proportionality  constant or the rate constant for the specific reaction rate

t = time of reaction

[tex]C_o[/tex] = initial concentration at time t

[tex]C _{\infty}[/tex] = final concentration at time t

[tex]C_t[/tex] = concentration at time t

To start with the value of t when t = 10 mins

[tex]K_1 = \dfrac{1}{10} \ In ( \dfrac{0.312 - 0}{0.312 - 0.089})[/tex]

[tex]K_1 = \dfrac{1}{10} \ In ( \dfrac{0.312 }{0.223})[/tex]

[tex]K_1 =0.03358 \ min^{-1}[/tex]

[tex]K_1 \simeq 0.034 \ min^{-1}[/tex]

When t = 20

[tex]K_2= \dfrac{1}{20} \ In ( \dfrac{0.312 - 0}{0.312 - 0.153})[/tex]

[tex]K_2= 0.05 \times \ In ( 1.9623)[/tex]

[tex]K_2=0.03371 \ min^{-1}[/tex]

[tex]K_2 \simeq 0.034 \ min^{-1}[/tex]

When t = 30

[tex]K_3= \dfrac{1}{30} \ In ( \dfrac{0.312 - 0}{0.312 - 0.200})[/tex]

[tex]K_3= 0.0333 \times \ In ( \dfrac{0.312}{0.112})[/tex]

[tex]K_3= 0.0333 \times \ 1.0245[/tex]

[tex]K_3 = 0.03412 \ min^{-1}[/tex]

[tex]K_3 = 0.034 \ min^{-1}[/tex]

When t = 40

[tex]K_4= \dfrac{1}{40} \ In ( \dfrac{0.312 - 0}{0.312 - 0.230})[/tex]

[tex]K_4=0.025 \times \ In ( \dfrac{0.312}{0.082})[/tex]

[tex]K_4=0.025 \times \ In ( 3.8048)[/tex]

[tex]K_4=0.03340 \ min^{-1}[/tex]

We can see that at the different time rates, the rate constant of [tex]k_1, k_2, k_3, and k_4[/tex] all have similar constant values

As such :

Rate constant k = 0.034 min⁻¹

Converting it to seconds ; we have :

60 seconds = 1 min

∴

0.034 min⁻¹ =(0.034/60) seconds

= 5.667 × 10 ⁻⁴ seconds

Rate constant k = 5.667 × 10 ⁻⁴

Answer:

Dew is liquid water droplets that form on grass, spider webs, and other things in the early morning or late evening. ... That means it turns from a liquid into a gas called "water vapor." When evening comes, the warm ground continues to radiate heat into

Answer:

2.81 × 10⁶ mm³

2.81 × 10⁻³ m³

Explanation:

Step 1: Given data

Length (l): 250 mm

Width (w): 225 mm

Thickness (t): 50 mm

Step 2: Calculate the volume of the textbook

The book is a cuboid so we can find its volume (V) using the following expression.

V = l × w × t = 250 mm × 225 mm × 50 mm = 2.81 × 10⁶ mm³

Step 3: Convert the volume to cubic meters

We will use the relationship 1 m³ = 10⁹ mm³.

2.81 × 10⁶ mm³ × 1 m³ / 10⁹ mm³ = 2.81 × 10⁻³ m³

Answer:

No

Explanation:

A white dwarf has a higher surface temperature than a red giant.

Answer: The molarity of solution is 0.453 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.

[tex]Molarity=\frac{n\times 1000}{V_s}[/tex]

where,

n = moles of solute

[tex]V_s[/tex] = volume of solution in ml

moles of [tex]C_2H_5OH[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{1.77g}{46g/mol}=0.0385mol[/tex]

Now put all the given values in the formula of molality, we get

[tex]Molarity=\frac{0.0385\times 1000}{85.0}[/tex]

[tex]Molarity=0.453[/tex]

Therefore, the molarity of solution is 0.453 M

Answer:

1.67 × 10⁻⁷ mol H₂O

3.14 × 10¹³ atoms deuterium

Explanation:

How many moles of water were injected?

We have 3.00 μg of gaseous H₂O. To calculate the number of moles of water we will use the following relationships:

[tex]3.00 \mu g \times \frac{1g}{10^{6}\mu g } \times \frac{1mol}{18.02g} = 1.67 \times 10^{-7} mol[/tex]

If the sample contains 0.0156% deuterium, how many deuterium atoms were injected?

We will use the following relationships:

1 mole of water contains 6.02 × 10²³ molecules of water.

There are 2 hydrogen atoms per water molecule.

0.0156% of hydrogen atoms are deuterium atoms.

[tex]1.67 \times 10^{-7} molH_2O \times \frac{6.02 \times 10^{23}moleculesH_2O }{1molH_2O} \times \frac{2atomsH}{1moleculeH_2O} \times 0.0156 \% = 3.14 \times 10^{13} atomsD[/tex]

Answer:

The correct answer is a. 0.223 grams, b. 3.36 × 10²¹ and c. 2.79 × 10⁻³ mol.

Explanation:

a. The volume of the solution given is 23.46 ml or 23.46 × 10⁻³ L, the molarity of NaOH is 0.238 M or 0.238 mol/L. Now the number of moles of NaOH will be,  

Number of moles = Molarity × Volume in Liters of solution

= 0.238 mol/L × 23.46 × 10⁻³ L  

= 5.5835 × 10⁻³ mol

Now the mass of NaOH will be,

= Moles × Molecular mass of NaOH

= 5.5835 × 10⁻³ mol × 39.997 g/mol  

= 223.322 × 10⁻³ grams

b) The number of moles in 23.46 ml is 5.5835 × 10⁻³ mol

Now the number of hydroxide ions found will be,  

= No. of moles × NA  

= 5.5835 × 10⁻³ × 6.022 × 10²³

= 3.36 × 10²¹

c) The balanced chemical equation is,

2NaOH + H₂SO₄ ⇒ Na₂SO₄ + 2H₂O

The number of moles of H₂SO₄ neutralized is,  

= Number of moles of NaOH taken/2

= 5.5835 × 10⁻³/2 mol

= 2.7917 × 10⁻³ mol

Answer:

C

Explanation:

When an apple is cut (or bruised), oxygen is introduced into the injured plant tissue. When oxygen is present in cells, polyphenol oxidase (PPO) enzymes in the chloroplasts rapidly oxidize phenolic compounds naturally present in the apple tissues to o-quinones, colorless precursors to brown-colored secondary products

Answer:

This states principle helps explain that an aircraft can achieve lift due to  the shape of its wings.

They wings are  shaped that way  so that that air flows faster over the top of the wing and slower underneath the wing .

In simple terms ;

Fast moving air equals low air pressure while slow moving air equals high air pressure

Explanation:

Answer:

Explanation:

Lithium, Potassium and Sodium follow each other in that order when it comes to reactivity.

Succinctly put, Lithium is the most reactive. Potassium is more reactive and Sodium is the least reactive.

Also, for Calcium, Strontium and Barium. It is the least reactive in this order.

Strontium, Barium, Calcium

That is, Strontium is more reactive than Barium, which is more reactive than Calcium. Calcium is the least reactive of the 3

Answer:

38,050,000,000,000 picoliters.

Explanation:

10-5=5, 7.61 x 5=38.05 (38.05L)

every liter is equal to 1000000000000 picoliters, so you go from there and just multiply 1000000000000 by 38.05.

Answer:

[tex]24540\frac{mg}{m^3}[/tex]

Explanation:

Hello,

In this case, since the 3% by volume is represented as:

[tex]\frac{3L\ CO}{L\ gas}[/tex]

By using the ideal gas equation we compute the density of CO:

[tex]\rho =\frac{MP}{RT} =\frac{28g/mol*1atm}{0.082\frac{atm*L}{mol*K}*298K}= 0.818g/L[/tex]

Then we apply the conversion factors as follows:

[tex]=\frac{3L\ CO}{100L\ gas}*\frac{0.818g\ CO}{1L\ CO} *\frac{1000mg\ CO}{1g\ CO} *\frac{1000L\ gas}{1m^3\ gas} \\\\=24540\frac{mg}{m^3}[/tex]

Regards.