10 Science Solved Sample Paper 2

Question: 17.
(1) What is an electric motor? Write the principle on which its working is based.
(2). What is short circuit? Give its possible cause. [5]

Answer:

1. Electric Motor is a device which transforms the electric energy into kinetic energy for doing work.
   The working of electric motor is based on ‘Fleming’s left hand rule’.
   This rule states that, “If we hold the fore finger, middle finger and thumb of our left hand, mutually perpendicular to each other, and if fore finger gives the direction of magnetic field, the middle finger gives the direction of current, then the thumb gives the direction of motion of the conductor due to force acting on it.
2. Short circuit: When live wire comes in contact with the neutral in between the circuit, then a lot of current flows abruptly through the circuit. Such a phenomenon is known as short circuit.
3. 
   When many electric appliances are connected in one circuit (through the same switch), then short circuit can occur.

Question: 18.
(1). Mention three advantages and three disadvantages of producing hydroelectricity by building dams on rivers. [5]

(2). Give reason for the following:
(i). A solar cooker box covered with a glass plate.
(ii). A solar cooker box is painted black from inside.

Answer: (2). (i) Glass plate increases the inside temp. of the solar cooker due to the green house effect of Infrared rays of sun.
(ii). Black colour absorbs the heat energy quickly.

Or
“Improvements in our lifestyle have resulted in greater amounts of waste generation.” Give two examples to support the given statement. Suggest one change that we can  incorporate in our lifestyle in order to reduce non-biodegradable waste.

Question: 19.
(1). Write the name and symbol of group 17 element belong to second period.
(2). Write electronic configuration of K(19). To which group of periodic table does it belong?
(3). What are substitution reaction? Give one example.
(4). What happens when acetic acid reacts with sodium bicarbonate? Give the chemical reaction involved.
(5). Why does carbon from covalent bonds? [5]

Answer:

1. F
2. K (9) = 2, 8, 8, 1  ⇒ 1st group
3. CH₄ + Cl₂     —-Sunlight—-→ CH₃Cl + HCl
4.  CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂
5. Carbon contains four electrons in its outermost shell.

Or
(1). Write the name and molecular formula of an organic compound having its name suffixed with -ol and having two carbon atoms in the molecule. With the help of a balanced chemical equation indicate what happens when it is heated with excess of concentrated H₂SO₄?
(2). What is substitution reaction? Give an example. [5]

Answer:           H     H
                             |       |
                   H — C — C — H      ⇒  C₂H₆O;
                             |       |
                            H    OH