FA2 PHYSICAL SCIENCE KEYSHEET CLASS 10

FORMATIVE ASSESSMENT – II (2021-22) 

PHYSICAL SCIENCE (English Medium) 

Key Sheet 

Class:X                                       Max.Marks : 20 ---------------------------------------------------------------------

I

01. D 1M 

02. B 1M 

03. A 1M 

04. C 1M 

05. D 1M 

II

06. Bleaching powder 1M 

07. No units 1M 

08. Aufbau rule 1M 

09. Total Internal Reflection 1M 

10. Dumbbell 1M 

III 

11. The following questions may be asked to know the formation of mirages : 2M 

 (i) What is a mirage? 

 (ii) How mirages are formed? 

 (iii) Is mirage a virtual image or real image? 

 (iv) Can we take the photograph of a mirage? 

(v) Do mirages form only in summer days? 

 (vi) What is the basic principle behind the formation of mirages? 

 12. (i) nlx method represents the arrangement of electrons in an atom. 2M 

(ii) It is the short hand notation consists of the principal energy level (n-value) the sub energy level (l-value) the number of electrons in the sub energy level (x-value) 

13. Uses of Baking Soda (NaHCO3): 2M 

(i) Baking soda is used for making Baking powder. Baking powder is used in the preparation of bread and cake to make them soft and spongy. 

(ii) Baking soda is also an ingredient in antacids. Being alkaline, it neutralizes excess acid in the stomach and provides relief. 

(iii) It is also used as soda-acid in fire extinguishers. 

 (iv) It acts as mild antiseptic. 

 (v) It is used sometimes for fast cooking.  

IV

14. Procedure of an activity to prove is constant during refraction : 4M 

 (i) Cover with white chart on the wooden plank. Draw a pro-circle. 

 (ii) There are two perpendicular lines, passing through the middle of the paper. 

 (iii) Let the intersecting point of these lines is O”.

 (iv) Here MM represents the line drawn along the interface of two media and NN represents the normal drawn to this line at ‘O’. 

 (v) Now place a semi-circular glass disc so that its diameter coincides with the interface line (MM) and its center coincides with the point O. 

 (vi) Point a laser light along NN in such a way that the light propagates from air to glass through the interface at point O and observe the path of laser light coming from other side of disc. (Use a black card board to observe the path of the light) 

 (vii) Send Laser light along a line which makes15o (incident angle) with NN and see that it passes through point O. 

 (viii) Measure its corresponding angle of refraction (r). 

 (ix) Note these values in table. Find sin i, sin r and also the ratio .

 (x) Do the same experiment for the angles of incidence such as 20o,25o, 30o,and 35o. 

Table

    (xi) In each and every case, we get the ratio as a constant. 

 (xii) Hence, Snell’s law is verified. 

 (OR) 

 As per the given table of pH values of different substances : 

 (i) D – solution is neutral. 

 (ii) C and H – solutions are strong alkali. 

 (iii) B and G – solutions are strong acids. 

 (iv) E and F – solutions are weak alkali.