If Nₐ is Avogadro’s number, what is the total number of valence electrons present in 4.2 g of N³⁻ ions?

1.	3.2 NA	2.	1.6 NA
3.	2.4 NA	4.	1.2 NA

Determine the number of significant figures in the final answer of the expression \(\large{\frac{(29.2-20.2)\times(1.79\times10^5)}{1.37}}\):

When 7.3 g of magnesium bicarbonate (Mg(HCO₃)₂) is decomposed by heating, how much carbon dioxide gas (in mL) is released at STP?

1. 1000 mL

2. 1120 mL

3. 2230 mL

4. 3240 mL

The amount of Zinc (atomic weight = 65) necessary to produce 224 mL of H₂ (at STP) by the reaction with dilute sulphuric acid will be: 

On complete decomposition, the volume of CO₂ released at STP on heating 9.85 g of BaCO₃ (atomic mass, Ba = 137) will be:

1. 1.12 L

2. 4.84 L

3. 2.12 L

4. 2.06 L

Specific volume of cylindrical virus particle is $6.02\times {10}^{-2}<mspace\; width="1em"></mspace>\mathrm{cc}/\mathrm{g}.$ Whose radius and length are 7 Å and 10 Å respectively. If ${\mathrm{N}}_{\mathrm{A}}=6.02\times {10}^{23},$ the molecular weight of the virus is:

1. \(15.4\ kg/mol\)
2. \(1.54 \ \times 10^4\ \ kg/mol\)
3. \(3.08 \ \times 10^4\ \ kg/mol\)
4. \(3.08 \ \times 10^3\ \ kg/mol\)

What is the weight of 1 × 10²³ molecules of CuSO₄·5H₂O?

1. 42.42 g

2. 41.42 g

3. 44.44 g

4. 48.94 g

The molality of 0.01 M Na₂CO₃ solution is:
(The density of the solution is 1.1 g/ml)

1. $9\times {10}^{-3}$

2. $1.8\times {10}^{-3}$

3. $4.5\times {10}^{-3}$

4. $1.1\times {10}^{-3}$

A chloride of a metal (M) has 65.5% of chlorine. 100 ml of vapor of the chloride of metal at STP weighs 0.72 g. The molecular formula of this metal chloride is:

1. MCl₃ 

2. MCl₄ 

3. M₂Cl₃ 

4. MCl₅ 

If $3.02\times {10}^{19}$ molecules are removed from 98 mg of H₂SO₄, then the number of moles of H₂SO₄ left are -

1. $0.1\times {10}^{-3}$

2. $9.5\times {10}^{-4}$

3. $1.2\times {10}^{-4}$

4. $0.5\times {10}^{-3}$