6.02 × 10²⁰ molecules of urea are present in 100 mL of its solution. The concentration of the solution is:
1. 0.01 M
2. 0.001 M
3. 0.1 M
4. 0.02 M

The volume occupied by one water molecule (density = 1 g cm^-3) is:

1. $9.0\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

2. $6.023\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

3. $3.0\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

4. $5.5\times {10}^{-23}$ $$ ${\mathrm{cm}}^3$

The volume of oxygen gas (O₂) needed to completely burn 1 L of propane gas (C₃H₈)  (both O₂ & propane measured at 0°C and 1 atm) will be:
1. 7 L
2. 6 L
3. 5 L
4. 10 L

The moles of lead (II) chloride that will be formed from a reaction between 6.5 g of PbO and 3.2 g of HCl are:
1. 0.044
2. 0.333
3. 0.011
4. 0.029

Concentrated aqueous sulphuric acid is 98% H₂SO₄ by mass and has a density of 1.80 g mL^-1. The volume of acid required to make one litre of 0.1 M H₂SO₄ solution is:

1. 11.10 mL

2. 16.65 mL

3. 22.20 mL

4. 5.55 mL

What is the number of moles of O-atom in 126 amu of ${\mathrm{HNO}}_3$?

1.  2

2.  $\frac{2}{{\mathrm{N}}_{\mathrm{A}}}$

3.  6

4.  $\frac{6}{{\mathrm{N}}_{\mathrm{A}}}$

Cisplatin, an anticancer drug, has the molecular formula $\mathrm{Pt}{\left({\mathrm{NH}}_3\right)}_2 {\mathrm{Cl}}_2$. What is the mass (in gram) of one molecule? (Atomic weights : Pt=195, H=1.0, N=14, Cl=35.5)

1.  $4.98\times {10}^{-21}$

2.  $4.98\times {10}^{-22}$

3.  $6.55\times {10}^{-21}$

4.  $3.85\times {10}^{-22}$

The conversion of oxygen to ozone occurs to the extent of 15% only. The mass of ozone that can be prepared from 67.2 L oxygen at 1 atm and 273 K will be:

1. 14.4 gm

2. 96 gm

3. 640 gm

4. 64 gm

A silver coin weighing 11.34 g was dissolved in nitric acid. When sodium chloride was added to the solution all the silver (present as $AgN{O}_3$) was precipitated as silver chloride. The weight of the precipitated silver chloride was 14.35 g. Calculate the percentage of silver in the coin.

1. 4.8%

2. 95.2%

3. 90%

4. 80%