Atomic mass refers to the mass of an atom. It depicts how many times an atom of an element is heavier than one-twelfth of the mass of one atom of carbon- 12 .

An atom of oxygen weighs 2 . 656 × 10 - 23 g. Calculate the number of atoms in 2 g of oxygen.

An atom of oxygen weighs 2 . 656 × 10 - 23 g Number of atoms present in 2 . 656 × 10 - 23 g of oxygen= 1 Therefore, 2 g of oxygen contains, 2 2 . 656 × 10 - 23 g = 7 . 53 × 10 22 atoms.

An atom of magnesium weighs 3 . 98 × 10 - 23 g. Calculate the number of atoms in 12 g of magnesium.

An atom of magnesium has a mass of 3 . 98 × 10 - 23 g. In 3 . 98 × 10 - 23 g of magnesium, number of atoms present = 1 So, in 12 g of magnesium, number of atoms present = 12 3 . 98 × 10 - 23 = 3 . 015 × 10 23 .

E M B I B E

Core science chemistry>Chapter 3 - Atoms and Molecules>EXERCISE 3A

V K Sally and R Goel Solutions for Chapter: Atoms and Molecules, Exercise 1: EXERCISE 3A

Author:V K Sally & R Goel

V K Sally Chemistry Solutions for Exercise - V K Sally and R Goel Solutions for Chapter: Atoms and Molecules, Exercise 1: EXERCISE 3A

Attempt the free practice questions on Chapter 3: Atoms and Molecules, Exercise 1: EXERCISE 3A with hints and solutions to strengthen your understanding. Core science chemistry solutions are prepared by Experienced Embibe Experts.

Questions from V K Sally and R Goel Solutions for Chapter: Atoms and Molecules, Exercise 1: EXERCISE 3A with Hints & Solutions

MEDIUM

9th CBSE

IMPORTANT

Core science chemistry>Chapter 3 - Atoms and Molecules>EXERCISE 3A>Q 4

Name one Indian and one foreign ancient thinker, who proposed the atomic nature of matter.

EASY

9th CBSE

IMPORTANT

Core science chemistry>Chapter 3 - Atoms and Molecules>EXERCISE 3A>Q 5

Name
(a) an element,
(b) an isotope of the element, used as atomic mass unit.

MEDIUM

9th CBSE

IMPORTANT

Core science chemistry>Chapter 3 - Atoms and Molecules>EXERCISE 3A>Q 6

In an experiment, $9.6$ g of sulphur bums completely in $9.6$ g of oxygen to produce $19.2$ g of sulphur dioxide. In another experiment, $9.6$ g of sulphur is made to bum completely in $100$ g of oxygen. What mass of sulphur dioxide is formed. Which law of chemical combination governs your answer?