English Medium Class 9 - CBSE Question Bank Solutions

What is the mass of 5 moles of sodium carbonate (Na2CO3) ?

(Atomic masses : Na = 23 u ; C = 12 u ; O = 16 u)

How many moles are represented by 100 g of glucose, C6H12O6 ? (C = 12 u, H = 1 u, O = 16 u)

Calculate the mass in grams of 0.17 mole of hydrogen sulphide, H2S. (Atomic masses : H = 1 u, S = 32 u)

Show by means of calculations that 5 moles of CO2 and 5 moles of H2O do not have the same mass. How much is the difference in their masses ?

Calculate the mole ratio of 240 g of calcium and 240 g of magnesium. (Ca = 40 u ; Mg = 24 u)

Define mole. What are the two things that a mole represents.

What weight of each element is present in 1.5 moles of sodium sulphite, Na2SO3 ?

(Atomic masses : Na = 23 u ; S = 32 u ; O = 16 u)

What is meant by ‘a mole of carbon atoms’ ?

Define gram atomic mass of a substance. How much is the gram atomic mass of oxygen ?

How many moles of oxygen atoms are present in one mole of the following compounds ?

1. Al₂O₃
2. CO₂
3. Cl₂O₇
4. H₂SO₄
5. Al₂(SO₄)₃

Which of the following pair of elements represents a mole ratio of 1 : 1 ?

Which of the following correctly represents 360 g of water ?

1. 2 moles of H₂O
2. 20 moles of water
3. 6.022 × 10²³ molecules of water
4. 1.2044 × 10²⁵ molecules of water

The ratio of moles of atoms in 12 g of magnesium and 16 g of sulphur will be :

Define atomic mass of an element.

What is meant by saying that 'the atomic mass of oxygen is 16' ?

Calculate the number of moles of magnesium present in a magnesium ribbon weighing 12 g. Molar atomic mass of magnesium is 24g mol^–1.

Calcium chloride when dissolved in water dissociates into its ions according to the following equation.

\[\ce{CaCl2} (aq) → {Ca^{2+} (aq) + 2{Cl}- (aq)}\]

Calculate the number of ions obtained from CaCl₂ when 222 g of it is dissolved in water.

The difference in the mass of 100 moles each of sodium atoms and sodium ions is 5.48002 g. Compute the mass of an electron.

Cinnabar (HgS) is a prominent ore of mercury. How many grams of mercury are present in 225 g of pure HgS? Molar mass of Hg and S are 200.6 g mol^–1 and 32 g mol^–1 respectively.

Raunak took 5 moles of carbon atoms in a container and Krish also took 5 moles of sodium atoms in another container of same weight.

1. Whose container is heavier?
2. Whose container has more number of atoms?