Q1. Why does the temperature remain constant when a solid converts into liquid?
OR
Ramu was asked to separate a mixture of common salt and ammonium chloride. He used
Sublimation technique to separate ammonium chloride. Does he use the correct method
to separate both the compounds and why?
Q2. Rutherford’s alpha particle scattering experiment showed that
i) Electrons have negative charge.
ii) The mass and positive charge of the atom is concentrated in the nucleus.
iii) Neutron exists in the nucleus.
iv) Most of the space in the atom is empty.
(a) (i) and (iii) (b) (ii) and (iv) (c) (i) and (iv) (d) (iii) and (iv)
Q3. Valency of an element ‘X’ is 3.Write the chemical formula of its oxide.
Q4. A particle is moving in a circular path of radius r. The displacement after half a circle would be:
(a) 0 (b) πr (c) 2r (d) 2πr
Q5. According to the third law of motion, action and reaction:
(a) always act on the same body.
(b) always act on different bodies in opposite directions.
(c) have same magnitude and directions.
(d) act on either body at normal to each other.
Q6. The value of acceleration due to gravity:
(a) is same on equator and poles (b) is least on poles
(c) is least on equator (d) increases from pole to equator
Solve these question and answers
Answers
Answer:
1.The temperature remains constant during the change of state because the heat energy which is supplied to change the state of matter is used in breaking the intermolecular forces and other attractive forces. Hence the temperature remains constant as all the heat is used up and no external heat is released or absorbed.
2.In Rutherford's alpha particle experiment, the scattered alpha particle has large deflection angles. This experiment showed that the positive matter of atom was concentrated in an very small volume and it gave the idea of nucleus of an atom.
3. X2O3
Answer: The chemical formula of the given oxide is X2O3. Explanation: The valency of element X is 3 and the valency of oxygen( in oxide) is 2.
4.2r
5.a)
6.The standard acceleration due to gravity (or standard acceleration of free fall), sometimes abbreviated as standard gravity, usually denoted by ɡ0 or ɡn, is the nominal gravitational acceleration of an object in a vacuum near the surface of the Earth. It is defined by standard as 9.80665 m/s2 (about 32.17405 ft/s2).