Which of the following represents the total number of valence electrons present in 0.53 g of Na₂CO₃?

1. $3.01\times {10}^{23}$

2. $7.22\times {10}^{22}$

3. $12.046\times {10}^{23}$

4. $6.023\times {10}^{23}$

Which of the following values is closest to the density of CCl₄ vapour (in g/L) at STP? 

1.  8.67

2.  6.87

3.  3.67

4.  4.26

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. $0.5\times {10}^{-3}$

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 

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. $1.1\times {10}^{-3}$

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

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

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

What mass of zinc (atomic mass = 65 g mol⁻¹) is required to produce 224 mL of H₂ gas at STP when zinc reacts with dilute sulphuric acid?