Case Study Questions for Class 9 Science Chapter 3 Atoms and Molecules
In CBSE Class 9 Science Paper, Students will have to answer some questions based on Assertion and Reason. There will be a few questions based on case studies and passage based as well. In that, a paragraph will be given, and then questions based on it will be asked.
Table of Contents
Here, we have provided case based/passage based questions for Class 9 Science Chapter 3 Atoms and Molecules. Students can practice these questions for their exam.
Case Study/Passage Based Questions
Question 1:
Read the following and answer any four questions from (i) to (iv).
A mole of an atom is a collection of atoms whose total mass is the number of grams equal to the
atomic mass. Since equal number of moles of different elements contain an equal number of atoms it becomes convenient to express the amounts of the elements in terms of moles. A mole represents a definite number of particles viz, atoms, molecules, ions or electrons. This definite number is called Avogadro number or Avogadro constant which is equal to 6.022 × 1023. Hence a mole represents 6.022 × 1023 particles of the substance. One mole of substance represents one gram-formula of the substance. One mole of a gas at standard temperature and pressure occupies 22.4 litres.
(i) How many grams of sodium must be taken to get 1 mole of the element ?
(a) 23 g
(b) 35.5 g
(c) 63.5 g
(d) 46 g
Answer
Answer: (a)(ii) What is the mass in grams of a single atom of chlorine? (Atomic mass of chlorine = 35.5)
(a) 6.54 × 1023 g
(b) 5.9 × 10–23 g
(c) 0.0025 g
(d) 35.5 g
Answer
Answer: (b)(iii) How many number of moles are there in 5.75 g of sodium ? (Atomic mass of sodium = 23)
(a) 0.25
(b) 0.5
(c) 1
(d) 2.5
Answer
Answer: (a)(iv) What is the mass in grams of 2.42 mol of zinc? (Atomic mass of Zn = 65.41)
(a) 200 g
(b) 25 g
(c) 85 g
(d) 158 g
