What volume of CO₂ gas will be produced at STP when 9.85 g of BaCO₃ is completely decomposed on heating?
Given: Atomic mass of Ba = 137

1. 1.12 L

2. 4.84 L

3. 2.12 L

4. 2.06 L

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?

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

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

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

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

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 correctly represents the number of particles present in 1 cc of N₂O gas at STP?

Which of the following statements is correct?

1. 1 mole of electrons weights 5.4 mg .
2. 1 mole of electrons weights 5.4 kg. 
3. 1 mole of electrons weights 0.54 mg. 
4. 1 mole of electrons has 1.6$\times {10}^{-19}$ C of charge.

How many moles of H₂SO₄ are present in 2.5 L of a 0.2 M solution?

1. 0.25

2. 0.5

3. 0.75

4. 0.2