English Medium इयत्ता ९ - CBSE Question Bank Solutions for Science

The atom of an element X contains 17 protons, 17 electrons and 18 neutrons whereas the atom of an element Y contains 11 protons, 11 electrons and 12 neutrons.

1. What type of ion will be formed by an atom of element X ? Write the symbol of ion formed.
2. What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from X ?
3. What type of ion will be formed by an atom of element Y ? Write the symbol of ion formed.
4. What will be the number of (i) protons (ii) electrons, and (iii) neutrons, in the ion formed from Y ?
5. What is the atomic mass of (i) X, and (ii) Y ?
6. What could the elements X and Y be ?

What is the numerical value of Avogadro number ?

What name is given to the number 6.022 × 1023 ?

What name is given to this number ?

What is the number of molecules in 1.5 moles of ammonia ?

Calculate the number of molecules in 4 g of oxygen.

If 32 g of sulphur has x atoms, then the number of atoms in 32 g of oxygen will be :

If 12 gram of carbon has x atoms, then the number of atoms in 12 grams of magnesium will be :

Which of the following has the maximum number of atoms ?

What weight of oxygen gas will contain the same number of molecules as 56 g of nitrogen gas ?

(O = 16 u ; N = 14 u)

What mass of nitrogen, N2, will contain the same number of molecules as 1.8 g of water, H2O ?

(Atomic masses : N = 14 u ; H = 1 u ; O = 16 u)

If one gram of sulphur contains x atoms, calculate the number of atoms in one gram of oxygen element.

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

How many grams of magnesium will have the same number of atoms as 6 grams of carbon ?
(Mg = 24 u ; C = 12 u )

The mass of one atom of an element X is 2.0 × 10–23 g.

Calculate the atomic mass of element X.

What could element X be ?

Classify each of the following on the basis of their atomicity.

1. F₂
2. NO₂
3. N₂O
4. C₂H₆
5. P₄
6. H₂O₂
7. P₄O₁₀
8. O₃
9. HCl
10. CH₄
11. He
12. Ag

Which has more number of atoms?

100g of N₂ or 100 g of NH₃

A gold sample contains 90% of gold and the rest copper. How many atoms of gold are present in one gram of this sample of gold?

Compute the difference in masses of one mole each of aluminium atoms and one mole of its ions. (Mass of an electron is 9.1×10^–28 g). Which one is heavier?

A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.

. A sample of ethane (C₂H₆) gas has the same mass as 1.5 ×1020 molecules of methane (CH₄). How many C₂H₆ molecules does the sample of gas contain?