class 9 chemistry chapter3
Answers
Answer:
NCERT Solutions for Class 9 Science Chapter 3
B BYJU'S
Atoms and Molecules
EXERCISE - 3.1
PAGE: 32
1. In a reaction, 5.3g of sodium carbonate reacted with 6 g of acetic acid. The products were 2.2 g of
carbon dioxide, 0.9 g water and 8.2 g of sodium acetate. Show that these observations are in agreement
with the law of conservation of mass.
+ carbon dioxide + water
Sodium carbonate + acetic acid - Sodium acetat
Solution:
Sodium carbonate + acetic acid - Sodium acetate + carbon dioxide + water
5.3g
6g
8.2g 2.2g 0.9g
As per the law of conservation of mass, the total mass of reactants must be equal to the total mass of
products
As per the above reaction, LHS = RHS i.e., 5.3g+ 6g = 2.2g+0.9g+8.2g= 11.3g
Hence the observations are in agreement with the law of conservation of mass.
2. Hydrogen and oxygen combine in the ratio of 1:8 by mass to form water. What mass of oxygen gas
would be required to react completely with 3 g of hydrogen gas?
Solution:
r mix in the ratio 1: 8.
We know hydrogen
For every 1g of hydrogen, it is 8g of oxygen.
Therefore, for 3g of hydrogen, the quantity of oxygen = 3 x 8 = 24g
Hence, 24g of
eaction with 3g of hydrogen gas.
tomic theory is the result of the law of conservation of mass?
3. Which postu
Solution
The relative number and types of atoms are constant in a given composition,' says Dalton's atomic theory,
which is based on the rule of con
"Atoms cannot be created nor be destroyed in a chemical reaction".
e law of definite proportions?
h postulate of Dalton's ator
Explanation: