States of Matter Test

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States of Matter Test - 30

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Weekly Quiz Competition

Question 1
1 / -0

'Equal volumes of all gases at the same temperature and pressure contain equal number of molecules'. This law is called as

A
Boyle's law

B
Charle's law

C
Avogadro's law

D
Gay Lussac's law

Solution

Avogadro's Law states that 'Equal volumes of all gases at the same temperature and pressure contain equal number of molecules'.
Hence, Option "C" is the correct answer.
Question 2
1 / -0

In the gas equation, $$PV=nRT$$:

A
$$n$$ is the number of molecules of a gas

B
$$n$$ moles of the gas have a volume $$V$$

C
$$V$$ denotes volume of one mole of the gas

D
$$P$$ is the pressure of the gas when only one mole of gas is present

Solution

$$(B)$$ $$n$$ moles of the gas have a volume $$V$$
An ideal gas is a gas whose pressure $$P$$, volume $$V$$, and temperature $$T$$ are related by the ideal gas law i.e.
$$PV = nRT$$,
where $$n$$ is the number of moles of the gas and $$R$$ is the ideal gas constant.
Question 3
1 / -0

Among the following substances, the lowest vapour pressure is exerted by:

A
water

B
alcohol

C
ether

D
mercury

Solution

Vapor pressure of mercury is very low (compared to a liquid like methyl alcohol) because the forces of interaction between the individual metal atoms of mercury is quite a bit stronger than the cohesive molecular forces (such as a hydrogen bonding) that holds together several molecules in case of alcohols,ethers and water.
Question 4
1 / -0

Which of the following is correct?

A
Van der waals radius of chlorine is bigger than nitrogen.

B
Covalent radius of nitrogen is bigger than chlorine.

C
Van der waals radius of chlorine is smaller than nitrogen.

D
All are correct.
Question 5
1 / -0

$$3$$ moles of $$P$$ and $$2$$ moles of $$Q$$ are mixed, what will be their total vapour pressure in the solution if their partial vapour pressures are $$80$$ and $$60$$ torr respectively?

A
$$80$$ torr

B
$$140$$ torr

C
$$72$$ torr

D
$$70$$ torr

Solution

We know that :
$$P_{total}=p_P+p_Q=p^0_Px_P + p^0_Qx_Q$$

where $$ p^0_P$$ and $$p^0_Q$$ are partial pressures of pure substances.
$$x_P$$ and $$x_Q$$ are mole fractions.

$$x_P=\dfrac{3}{5}=0.6$$

$$x_Q = \dfrac{2}{5}=0.4$$

hence
$$P_{total}=p^0_Px_P + p^0_Qx_Q= 80\times 0.6 + 60\times 0.4 =72torr$$
Question 6
1 / -0

The vapour pressure of a solvent at $$293$$K is $$100$$ mm Hg. Then the vapour pressure of a solution containing $$1$$ mole of a strong electrolyte $$(AB_2)$$ in $$99$$ moles of the solvent at $$293$$ K is:
(Assume complete dissociation of solute)

A
$$103$$ mm Hg

B
$$99$$ mm Hg

C
$$97$$ mm Hg

D
$$101$$ mm Hg

Solution

Let us consider the problem:
$$\frac{{({P_A}^0 - {\rm{ }}{P^0})}}{{{P_A}^0}} = i\frac{{({n_B})}}{{({n_A} + {n_B})}}$$
Since,
$$\frac{{\left( {100 - {P_A}} \right)}}{{100}} = 3{\rm{ }}\left[ {\frac{1}{{\left( {99 + 1} \right)}}} \right]$$
Since,
$$100 - {P_A} = 3$$
Hence the solution is $${P_A} = 97 mm$$ of $$Hg$$.
Question 7
1 / -0

According to Avogadro's hypothesis, equal volumes of gases under the same conditions of temperature and pressure will contain:

A
the same number of molecules

B
different number of molecules

C
the same number of molecules only if their molecular masses are equal

D
the same number of molecules if their densities are equal.

Solution

According to avogadro's hypothesis, equal volumes of gases under the same conditions of temperature and pressure will contain, the same no. of molecules.
For eg. One volume of hydrogen combines with one volume of chlorine to produce two volumes of HCl gas.
$$H_2\\1vol$$ $$+$$ $$Cl_2=\\1 vol$$ $$2HCl\\2 vol$$
Question 8
1 / -0

A solution at $$20^o$$C is composed of $$1.5$$ mol of benzene and $$3.5$$ mol of toluene. If the vapour pressure of pure benzene of pure benzene and pure toluene at this temperature are $$74.7$$ torr and $$22.3$$ torr. respectively, then the total vapour pressure of the solution and the benzene mole fraction in equilibrium with it will be, respectively.

A
$$38.0$$ torr and $$0.589$$

B
$$30.5$$ torr and $$0.389$$

C
$$35.8$$ torr and $$0.280$$

D
$$35.0$$ torr and $$0.480$$

Solution

Let us the problem.
According to the raoult's law is used which states that for a solution of volatile liquids, the partial vapour pressure of each liquid in the solution is directly proportional to its mole fraction.
$${X_{benzene}} = \frac{{1.5}}{5} = 0.3$$
$${X_{toluence}} = \frac{{3.5}}{5} = 0.7$$
$${P_T} = 74.7 \times 0.3 + 0.7 \times 22.3$$
$$ = 22.41 + 15.61$$
$$= 38.02\,torr$$
$${Y_{benzene}} = \frac{{22.41}}{{38.02}} = 0.589$$
Question 9
1 / -0

If the absolute temperature of a gas is doubled and the pressure is reduced to one-half, the volume of the gas will

A
remain unchanged

B
be doubled

C
increase four-fold

D
be reduced to $$1/4th$$

Solution

We know that $$\frac{P_1V_1}{T_1}$$ = $$\frac{P_2V_2}{T_2}$$
Volume of the gas = v
Pressure $$P_1$$ = p
Pressure $$P_2$$ = $$\frac{1p}{2}$$
Temperature = $$T_1$$ = t
Temperature = $$T_2$$ = 2t
$$V_2$$ = $$P_1V_1T_2/T_1$$
= $$( p\times v\times2t)$$ / $$(2t\times p)$$
= v
That means $$V_2 = V_1$$
So it increases four-fold so C is the correct option.
Question 10
1 / -0

For an ideal gas, a number of moles per liter in terms of its pressure P, gas constant R and temperature T is:

A
PT/R

B
PRT

C
P/RT

D
RT/P

Solution

According to Ideal Gas Equation, $$PV =nRT$$
P is the pressure, V is the volume, n is the number of moles, R is gas constant and T is the temperature.
Therefore number of moles per litre,
$$ \frac{n}{v} $$ = $$ \frac{P}{RT} $$
Therefore, C is the correct option.

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States of Matter Test - 30

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States of Matter Test - 30

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Question 1

Boyle's law

Charle's law

Avogadro's law

Gay Lussac's law

Solution

Question 2

$$n$$ is the number of molecules of a gas

$$n$$ moles of the gas have a volume $$V$$

$$V$$ denotes volume of one mole of the gas

$$P$$ is the pressure of the gas when only one mole of gas is present

Solution

Question 3

water

alcohol

ether

mercury

Solution

Question 4

Van der waals radius of chlorine is bigger than nitrogen.

Covalent radius of nitrogen is bigger than chlorine.

Van der waals radius of chlorine is smaller than nitrogen.

All are correct.

Question 5

$$80$$ torr

$$140$$ torr

$$72$$ torr

$$70$$ torr

Solution

Question 6

$$103$$ mm Hg

$$99$$ mm Hg

$$97$$ mm Hg

$$101$$ mm Hg

Solution

Question 7

the same number of molecules

different number of molecules

the same number of molecules only if their molecular masses are equal

the same number of molecules if their densities are equal.

Solution

Question 8

$$38.0$$ torr and $$0.589$$

$$30.5$$ torr and $$0.389$$

$$35.8$$ torr and $$0.280$$

$$35.0$$ torr and $$0.480$$

Solution

Question 9

remain unchanged

be doubled

increase four-fold

be reduced to $$1/4th$$

Solution

Question 10

PT/R

PRT

P/RT

RT/P

Solution

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