10TH CBSE SCIENCE 2 MARKS TEST WITH ANSWERS 8 FEB 2025

   1. Define excretion. Write two vital functions of kidney.                                             

  2.Why Bile juice is considered to be an important secretion of liver in the process of digestion?     

3. An object 5cm in length is placed at a distance of 20 cm in front of a convex mirror of radius of curvature 30 cm. Find the position of image, its nature and size.                  

 

OR

 

  Define power. A doctor has prescribed corrective lens of power +1.5 D.

 Find the focal length of the lens. Is the prescribed lens diverging or converging?

 

4.  When a few drops of BARIUM CHLORIDE solution are added to an aq solution of SODIUM SULPHATE a white precipitate is obtained

1.     Write balanced chemical equation for the chemical reaction involved

2.     Write the other name of the chemical reaction..  .

5. How can three resistors of 2 Ω ohm, 3 Ω ohm and 6 Ω can be connected to give a       total resistance of                                                                                                              

(i)4 Ω                      (ii) 1 Ω

OR

Why does the cord of an electric oven does not glow while its heating element does?

6.What is ozone and how does it affect any ecosystem?              

ANSWERS

   

1.	i.          Definition      ii.          (a) Osmoregulation (b) Filtration
2.	Two reasons due to which bile juice is considered to be an important secretion of liver are as follows (i) Bile salts which are present in bile juice breakdown large globule of fat into small globules to increase the efficiency of enzyme action. (ii) It makes the acidic food alkaline, so that pancreatic enzymes can act on it.
3.	ho = 5 cm u = -20 cm r = 30 cm f = 30/2 = 15 cm                                                                                         1/f = 1/u + 1/v 1/v = 1/f – 1/u = 1/15 – 1/-20 = 7/60 1/v = 7/60 v = 60/7 = 8.57 cm                                                                                            m = hi/ho = -v/u -60/7 x -20 = hi/5 h1 = -60 x 5/-7x20 = 2.14 cm                                                                            Image is diminished, erect & virtual  OR Define                               __________________                                             p = +1.5 D p = 1/f                         f = 1/p = 1/1.5 = 10/15 = 0.66m                                                                        f = 0.66 x 100 = 66 cm                                                                                       Converging lens
4.	The balanced chemical equation for the reaction involved is BaCl2(aq) + Na2SO4 (aq) → BaSO4 (White ppt.) + 2NaCl(aq) (ii) The other name of this precipitation reaction is double displacement reaction because ions or group of atoms in both the reactant molecules are displaced by each other
5.	(i)              If 3 Ω & 6 Ω are connected in parallel Equivalent resistance = 1/(1/3 + 1/6) = 2 Ω                                                          This combination is connected in series with                       2 Ω = 2 Ω + 2 Ω = 4 Ω (ii)            All three resistance are connected in parallel.                      Equivalent resistance = 1/(1/2 + 1/3 + 1/6) = 1 Ω OR Correct explanation of heating effect of current

                          

6.	Ozone is triatomic molecule of oxygen O3.                                                   Effects on ecosystem (i)It protects against ultraviolet rays. (ii)Dissipates the energy of UV rays by undergoing dissociation.                    (iii)It is highly toxic.