CBSE Sample Paper Class X Science
1. What change in colour is observed when white silver chloride is left exposed to sunlight ? What type of chemical reaction is this ? 1
2. Which gas is generally liberated when a dilute solution of hydrochloric acid reacts with an active metal ? I
3. Arrange the following metals.in a decreasing order of activity : 1
Na, K, Cu, Ag
Na, K, Cu, Ag
4. What kind of mirrors are used in big shopping stores to watch activities of customers ? 1
5. Draw a ray diagram to determine the position of image formed of an object placed between the pole and the focus of a concave mirror. 1
6. What will be the observed colour of sky on a planet where there is no atmosphere ? Why ? 1
7. What is meant by ‘water of crystallisation’ of a substance ? Describe an activity to show that blue copper sulphate crystals contain water of crystallisation. –
8. What is a redox reaction ? When a magnesium ribbon burns in air with a dazzling flame and forms a white ash, is magnesium oxidised
or reduced ? Why ? 2
9. The refractive index of water is 1-33 and the speed of light in air is
3 x 10 ms . Calculate the speed of light in water. – 2
10. (a) What is the shape of the graph obtained by plotting potential
difference applied across a conductor against the current flowing through it ?
What does the slope of this V -1 graph at any point represent ?
11. Give reasons for the following observations :
(i) Ionic compounds in general have high melting and boiling points.
(ii) Highly reactive metals cannot be obtained from their oxides by heating them with carbon.
(iii) Copper vessels get a green coat when left exposed to air in rainy