Mole Concept

Q. 20. if average molecular weight of air is 29, then assuming N2 and O2 gases are there which option are correct regarding composition of air : 1] 75% by mass ofN2 2] 75% by moles of N2 3] 72.41% by mass of N2

Q.

What is the molecular weight of $\mathrm{NaOH}$?

Q.

Atomic mass of bromine is 80 g. The mass of four moles of molecular bromine (Br₂) is:

1. 640 g

2. 80 g

3. 40 g

4. 320 g

Q.

Mass of 6.022 x 10²²molecules of CO₂is about:

1. 12 g

2. 1.4 g

3. 4.4 g

4. 2.2 g

Q. 27.6 g of $K_{2}C{O}_3$ was treated by a series of reagents so as to covert all of its carbon to $K_{2}Z{n}_3\left[Fe\right(CN{)}_6{]}_2$. Calculate the mass of the product:
(Molecular mass of $K_{2}Z{n}_3\left[Fe\right(CN{)}_6{]}_2$ = 698 u)

1. 13.60 g
2. 12.57 g
3. 15.89 g
4. 11.63 g

Q.

A gold sample contains $90\%$gold and the rest copper. How many atoms of gold are present in one gram of this sample of gold?

Q.

How did Avogadro gets his number?

Q.

Equivalent Weight of CaCl₂

Q. Which of the following species have maximum number of unpaired electron?

1. 
2. 
3. 
4. 

Q. Calculate the atomic mass of $S$ - atom in grams?

1. $1.062\times {10}^{-22}$
2. $5.31\times {10}^{-23}$
3. $1.062\times {10}^{-23}$
4. $5.31\times {10}^{-22}$

Q. On heating 1.763 g of hydrated BaCl2 to dryness, 1.505 g of anhydrous salt remained. Hence the formula of the hydrate is (Atomic weight of Ba = 137)

Q.

1.5 mol of $O_2$ combines with $Mg$ to form the oxide $MgO$. The mass of $Mg$ (at. mass 24) that has combined is:

1. 72 g
2. 36 g
3. 48 g
4. 24 g

Q. what is the mass of H2so4 which contains 80g of oxygen?

Q.

At STP weight of $1litre$ of a gas is $3.16grams$ and weight of $1litre$ of Hydrogen is $0.09gm$. If molecular weight of Hydrogen is 2, molecular weight of the gas is

1. 70.8

2. 64.4

3. 32.2

4. 44.6

Q. 6. Why the value of kp and kc depends on the temperature only but not on the concentration or the pressure or volume

Q.

If the atomic weight of nitrogen is 14.0, what is the mass of one mole of nitrogen gas, ${\mathrm{N}}_2$?

Q. Calculate the atomic mass of $Ca$ atom in g?

1. $3.32\times {10}^{24}$ g
2. $3.32\times {10}^{-23}$ g
3. $6.64\times {10}^{-23}$ g
4. $6.64\times {10}^{-24}$ g

Q. Equal volumes of oxygen gas and a second gas weigh 1.00 and 2.375 grams respectively under the same experimental conditions. Which of the following is the unknown gas?

1. $NO$
2. $S{O}_2$
3. $C{S}_2$
4. $CO$

Q. 47. What is stp and ntp? What are there pressure and temperature?

Q. /(3)Only b, c55 280 mL of sulphur vapours weigh 3.2 g at NTPalculate the number of atoms present permolecule(2) 4(4 86

Q. 28 At what temperature will O2 have the same density as N2, at 0^° C, assuming pressure remainsconstant?(1) 39^° C(3) 273 K(2) 39 K(4) 312^° C

Q. which of these weights more 1)32g of o2 2)2g atom of nitrogen 3)0.5 mol of fe 4)3.01×10^{23

Q. Calculate the molar mass of ${CH}_4$.

Q. A sample of Urea $\left(C{H}_4{N}_{2}O\right)$ has $42.5\%$ N. What is the percentage purity of the sample?

1. 92.07

2. 91.07

3. 100

4. 93.07

Q.

Calculate the relative molecular mass of ${\mathrm{H}}_2{\mathrm{SO}}_4$.

Q.

100 mL of PH₃ on heating forms P and H₂. The volume change in the reaction is:

1. An increase of 50 mL

2. An increase of 100 mL

3. An increase of 150 ml

4. A decrease of 50 mL

Q. The number of moles of $H_2$ present in $0.112\text{L}$ of $H_2$ gas at STP is:

1. $5\times {10}^{-3}\text{mol}$
2. $5\times {10}^{-2}\text{mol}$
3. $6\times {10}^{-3}\text{mol}$
4. $5\times {10}^{-4}\text{mol}$

Q. Find the mass of $3.011\times {10}^{26}$ molecules of $N{H}_3$ in grams.

1. $8599.81\text{g}$
2. $8249.81\text{g}$
3. $8349.81\text{g}$
4. $8499.81\text{g}$

Q. $O_2$ gas at STP contained in a flask was replaced by $S{O}_2$ under same conditions. The weight of $S{O}_2$ will be:

1. Equal to that of $O_2$
2. Half that of $O_2$
3. Twice that of $O_2$
4. One-fourth of $O_2$

Q. CsBr crystallises in a body centred cubic lattice. Theunit cell length is 436.6 pm. Given that the atomicmass of Cs-133 and that of Br-80 amu andAvogadro number being 6.023 x 1023 mol-1 thedensity of CsBr is:(1) 42.5 g cm-3(3) 8.25 g cm 3(2) 0.425 g cm-3(4) 4.25 g cm-3