Question

all the mcqs of atoms and molecules ​

Answer 1

Answer:

yes I am in 10th class

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Answer 2

Answer:1. The atomic symbol of silver is —————

(a) Si

(b) S

(c) Au

(d) Ag

Ans: (d)

Solution: The atomic symbol of silver is Ag

2. A box contains some identical red colour balls labelled as A each weighing 2 g. Another box contains identical blue colored balls, labelled as B, each weighing 5 g. In the combinations AB, AB2, A2B and A2B3 which is applicable?

(a) Law of Definite proportion

(b) Law of multiple proportion

(c) Law of conservation of mass

(d) None of the above

Ans: (b)

Solution: According to the law of multiple proportion if an element forms more than one compound with another element for a given mass of an element, masses of other elements are in the ratio of the small whole number.

3. What is the value of Avogadro’s number?

(a) 6.02 x 10-23

(b) 6.02 x 1023

(c) 6.02 x 10-22

(d) 6.02 x 1022

Ans: (b)

Solution: The value of Avogadro’s number is 6.02 x 1023

4. What is the chemical formula of sodium carbonate?

(a) Na2CO3

(b) NaHCO3

(c) NaCO3

(d) Na2HCO3

Ans: (a)

Solution: The chemical formula of sodium carbonate is Na2CO3

5. Which of the following is the correct pair of atom and its atomic symbol?

(a) Sulphur – Su

(b) Potassium – P

(c) Phosphorus -P

(d) Sodium- S

Ans: (c)

Solution: The correct pair of atom and its atomic symbol is Phosphorus -P

6. How many moles are present in 40 g of He?

(a) 5 moles

(b) 20 moles

(c) 6 moles

(d) 10 moles

Ans: (d)

Solution: 1 mole of He = 4 gm. ⇒ 40 gm of He = 10 moles

7. Atomic mass of Chlorine is ————– (u)

(a) 34

(b) 34.5

(c) 35

(d) 35.5

Ans: (d)

Atomic mass of Chlorine is 35.5 u

8. 46 gm of sodium is equal to ————-

(a) 7 moles

(b) 1.5 moles

(c) 2 moles

(d) 1 mole

Ans: (c)

Solution: 1 mole of sodium = 23gm, 46 gm of sodium = 2 moles

9. The formula of Ammonium Sulphate is —————–

(a) NH4SO4

(b) NH4SO2

(c) (NH4)2SO4

(d) NH2SO4

Ans: (c)

Solution: The formula of Ammonium Sulphate is (NH4)2SO4.

10. The atomic symbol of Iron is —————.

(a) I

(b) Fe

(c) Ir

(d) Au

Ans: (b)

Solution: The atomic symbol of Iron is Fe.

Explanation: