Key Sheet SA1 PHYSICAL SCIENCE 2022

SUMMATIVE ASSESSMENT

PHYSICAL SCIENCE

KEY SHEET

SECTION -I 

1. Condensation

2. Pink 

3. Neutralization

 4.A-Q C/V      B-R>1

5. Convex lens

6. Aufbau

7.18

8. Li, Na, K 

9.  Rubidium 

10. 80 Cal/g 

11. P is Correct Q is incorrect 

12. 90°

SECTION-II 

13. 27+273= 300K

14. Spherical 

15. Nature of the material and Wavelength

16. 0-14

17. VII A or 17th group elements

18. The line joining the points C1  and C2 is called principal axis.

19. (i) Pure acetic acid is a weak acid. 

 (ii) The concentration of hydrogen ions in acetic acid is less. 

 (iii) So it does not convert blue litmus in to red.

20. The amount of water vapour present in air is called Humidity. 

21. (i) Plaster of Paris should be stored in moisture-proof container. 

 (ii) Because it turns into Gypsum after reacting with moisture present in air. 

 (iii) Also it sets into hard solid. 

22. (i) If specific heat is high, the rate of raise or fall in temperature is low. 

 (ii) Water melon consists of more water. 

 (iii) The specific heat of wate r is high. (S= 1 cal/g-°C)

 (iv) So watermelon takes long time to raise its temperature. 

 (v) Hence Watermelon brought out from a fridge retains its coolness for a long time. 

23. Uses of Washing soda (Na2CO3) :

 (i) Sodium carbonate (washing soda) is used in glass, soap and paper industries.

 (ii) It is used in the manufacture of sodium compounds such as borax.

 (iii) Washing soda can be used as a cleaning agent for domestic purposes.

 (iv) It is used for removing permanent hardness of water.

24. (i) When wet clothes kept in open place, due to large area exposed to air, the water molecules absorb heat from surroundings and change its state by leaving the clothes dry on wind blows. 

 (ii) This process is evaporation.

25. (i) The electron belongs to 3s orbital.

 (ii) The element is Sodium. 

26. Changes in atomic size:

 (i) In groups, the atomic size of an atom increases from top to bottom.

 (ii) In periods, the atomic size of an atom decreases from left to right.

27. (i) Due to refraction at water and air interface, the fish appears to be raised and seems to be close to the surface. 

 (ii) This is called apparent depth. 

 (iii) The shooter aims the gun to apparent position of fish instead of real position. 

 (iv) Hence it is very difficult to shoot a fish swimming in water.