HPE-book-7-final-for-press

Exercise

1. Choose the best answer.

a. A liquid has_________.

i. fixed shape and volume

ii. fixed shape but no fixed volume

iii. fixed volume but not fixed shape

iv. neither fixed shape nor fixed volume.

b. Na is symbol of _________.

i. nitrogen ii. neon iii. sodium iv. nickel.

c. Which of the given substances is made by only one type of atoms?

i. water ii. sodium chloride iii. carbon dioxide iv. iron

d. Which of the following is not a subatomic particle of atom?

i. proton ii. neutron iii. electron iv. ion

e. Which of the following is the molecular formula for calcium chloride?

i. Ca2Cl ii. CaCl iii. CaCl2 iv. CaCl3

f The number of electron in a shell is distributed by _________ rule.

i. n2 ii. 2n2 iii. 3n2 iv. 4n2 .

g Which of the following is a reversible change?

i. milk to curd ii. water and ice

iii. digestion of food iv. burning of wood.

2. Fill in the blanks with suitable words:

a. _______is non metal, which is found in liquid state.

b. The smallest particle of an element which can take part in chemical
reaction is_______.

c. In general atom, the number of proton is equal to the number of______.

d. Water molecule consists of 2 atoms of________ and 1 atom of______.

e. Electron is _________ and proton is _______ charged particles.

f. The number of neutron in an atom of calcium is _______.

g. Atomic________ is the sum of protons and neutrons in an atom.

h. The combining capacity of an element is called________.

i. Physical change is _______ change.

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3. Put a tick (√) for the correct statement and a cross (×) for incorrect one.

a. The intermolecular force of attraction is greatest in gases.

b. Elements occur naturally only.

c. Elements cannot be further broken down to simpler form.

d. The outermost shell cannot have more than 8 electrons.

e. The number of neutrons determines the atomic number of an element.

f. Water is a compound.

g. No new substances are formed during chemical change.

4. Match the following elements with its symbol

Helium N

Argon K

Calcium He

Nitrogen P

Neon Ca

Gold Ne

Potassium Au

Phosphorus Ar

5. Give one word.

a. Pure substance that cannot be broken into simpler form.

b. Combination of two or more elements in fixed proportion.

c. Positively charged particles in the nucleus of an atom.

d. Negatively charged particles in the nucleus of an atom.

e. Chargeless particles in the nucleus of an atom.

f. The combining capacity of an element or a compound.

6. Define the following terms.

a. Atom b. Molecule c. Compound d. Valency.

7. Answer the following question.

a. Define matter. What are the three states of matter?
b. Write two properties of solid and liquid.
c. What are pure and impure substance? Give examples.
d. What is symbol? Write symbols of any 5 elements.
e. What is an atom composed of?

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f. What is meant by atomic mass and atomic number?
g. What is electronic configuration? Write an importance of 2n2 formula.

h. What is molecular formula? How is it written?

i. Mention the importance of molecular formula. Write down the
molecular formula of

(a) water (b) sodium chloride (c) carbondioxide (d) ammonia

j. What is physical and chemical change? Give examples of each.

8. Give reasons of the following:

a. Gases do not have fixed shape and volume.

b. Atom as a whole is electrically neutral.

c. Changing of water into vapour is a physical change.

d. The rusting of iron is called a chemical change.

9. Differentiate between.

a. Atom and molecule

b. Element and compound

c. Atomic number and atomic mass

d. Physical and chemical change

10. Show the electronic configuration of.

a. Carbon b. Sodium c. Argon d. Calcium

Activity

Write the molecular formula of the following compounds by using criss
cross method.

a. Sodium chloride b. Hydrochloric acid c. Ammonia
d. Calcium oxide e. Calcium carbonate f. Sodium oxide
g. Aluminium chloride

Project work

Draw atomic structure of elements of atomic number 1 to 20 on a
chart paper and paste on the wall of your classroom.

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