English Medium Class 9 - CBSE Question Bank Solutions

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?

In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed?

Match the names of the Scientists given in column A with their contributions towards the understanding of the atomic structure as given in column B

The atomic number of calcium and argon are 20 and 18 respectively, but the mass number of both these elements is 40. What is the name given to such a pair of elements?

Helium atom has 2 electrons in its valence shell but its valency is not 2, Explain

An element X has a mass number 4 and atomic number 2. Write the valency of this element?

Which of the following are covered by a single membrane?

Which of the following are chemical changes?

(i) Decaying of wood

(ii) Burning of wood

(iii) Sawing of wood

(iv) Hammering of a nail into a piece of wood

Two chemical species X and Y combine together to form a product P which contains both X and Y

\[\ce{X + Y -> P}\]

X and Y cannot be broken down into simpler substances by simple chemical reactions. Which of the following concerning the species X, Y and P are correct?

(i) P is a compound

(ii) X and Y are compounds

(iii) X and Y are elements

(iv) P has a fixed composition

Classify the following as physical or chemical properties

Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.

Classify the following as physical or chemical properties

Most metal oxides form alkalis on interacting with water.

On heating calcium carbonate gets converted into calcium oxide and carbon dioxide.

(a) Is this a physical or a chemical change?

(b) Can you prepare one acidic and one basic solution by using the products formed in the above process? If so, write the chemical equation involved.

Classify each of the following, as a physical or a chemical change. Give reasons.

(a) Drying of a shirt in the sun.

(b) Rising of hot air over a radiator.

(c) Burning of kerosene in a lantern.

(d) Change the colour of black tea by adding lemon juice to it.

(e) Churning of milk cream to get butter.

Why does the percentage of gases like oxygen, nitrogen and carbon dioxide remain almost the same in the atmosphere?

Can you name the two organelles we have studied that contain their own genetic material?