CLASS VII - SCIENCE - WORKSHEET-3, MATTER AROUND US - ANSWERS
WORKBOOK - 3
MATTER AROUND US
I. Multiple choice questions.
1. Among the following statements, which one is wrong about an atom?
Ans: d. An atom is indivisible
2. Which of the following element is not in the top three most abundant atoms on the earth?
Ans: b. Hydrogen
3. Which of the following is an element?
Ans: b. Sulphur
4. The elements like magnesium and phosphorous are used in_______
Ans: b. Making crackers
II. Match the following
5. Match the molecules with their Ball and Stick models
Hydrogen chloride

Carbon dioxide
Ammonia
III. Fill in the blanks:
6. There are 118 elements till date. Among these_______ elements occur naturally and _______ elements are synthesised artificially in the laboratory.
Ans: 94 and 24
7. The most abundant type of atom in the universe is _________.
Ans: Hydrogen atom
IV. Answer briefly:
8. Decode the given molecular diagram into a chemical equation.
9. Classify the following molecules as moles of element or moles of compound.
Ans:
Element Compound
P4 HNO3
S8 H3PO4
Cl2 CH4
10. Sodium is a corrosive metal. Chlorine is a poisonous gas. But, sodium chloride (Common salt) , the compound formed from these elements is an essential ingredient in our food. Justify sodium chloride is safe to use based on the properties of compounds.
Ans:
Sodium chloride is a compound.
The compound composed of these ions exhibits properties entirely different from the properties of the elemental sodium and chlorine.
So it is safe to use sodium chloride in our food.