This document contains 25 science questions for a 9th grade class exam. The questions cover topics like pure substances, health conditions, tissues, atomic structure, crop production, stomata functions, organism classification, amphibian and reptile differences, phloem constituents, molecular mass, food and health, the greenhouse effect, homogeneous and heterogeneous mixtures, soil fertility, Bohr's atom model, electron configuration in sodium, atom definition, factors affecting crop production, cloud formation, preventing infectious diseases, and classifying elements, compounds and mixtures. The exam has a maximum score of 60 marks.

1. AD PUBLIC SR SEC SCHOOL CHANDHUT
SUBJECT :- SCIENCE CLASS :- 9th
MM :- 60
1. What is meant by a pure substance ? (2)
2. State any two conditions essential for good health . (2)
3. Define the term “tissue” . (2)
4. If an atom has 8 protons and 10 neutrons .Find atomic number and mass number of
atom . (2)
5. Explain any one method of crop production which ensures high yield . (2)
6. What are the functions of stomata ? (2)
7. What are the advantages of classifying organisms ? (2)
8. What are differences between amphibians and reptiles ? (2)
9. What are the constituents of the phloem ? (2)
10. Define molecular mass ? (2)
11. Why are we normally advised to take bland and nourishing food when we are sick ? (2)
12. What is the green house effect ? (2)
13. Which of the following materials fall in the category of a “pure substance”? (a)ice
(b)milk (c)iron (d)mercury (e)brick (f) wood (2)
14. Why is water essential for life ? (2)
15. 12.044×10^23 number of He atoms find the number of moles from number of particles
given Avogadro number = 6.022 ×10^23 (2)
16. List the points of differences between homogeneous and heterogeneous mixtures ?
(3)
17. Compare the use of manure and fertilizers in maintaining soil fertility ? (3)
18. Describe the Bohr’s model of atom with diagram ? (3)
19. Write the distribution of electrons in sodium atom ? (3)
20. Define atom . describe Thomson’s model of an atom . (1+2)
21. How do biotic and abiotic factors affect crop production ? (3)
22. How are clouds formed ? (3)
23. What precautions can you take in your school to reduce the incidence of infectious
diseases ?(3)
24. Calculate molecular masses of ZnO, Na2O, K2CO3 , given atomic mass of Zn=23 u ,
K=39 u , C=12 u , and O=16 u (3)
25. Classify the following into elements ,compounds,and mixtures . (a) sodium (b)soil
(c)sugar solution (d)silver (e)tin (f)silicon (g)coal (h)air (i)soap (3)