Question

Q] Choose one option and explain how it is correct
1) A body is thrown vertically upward from the surface of the ground with the velocity of 9.8 m/s. What maximum height it will reach?
(answer should come 4.9 m)

2) The reactants and the products of a chemical reaction are in different physical states. Then what is the type of the reaction?
a) Heterogeneous        b) Homogeneous    c) Exothermic         d) Endothermic

3) Name the gas liberated when dilute hydrochloric acid reacts with zinc.
a) Oxygen             b) Carbon dioxide             c) Hydrogen         d) Carbon monoxide

Answer 1

1) we choose the following eq, as we are not involved with time variable. the other equations have time t.

v² = u² + 2 a S
0² = 9.8² - 2 *9.8 * S
S = 9.8 * 9.8 / 2 * 9.8 = 4.9 meters

2) Heterogeneous - involves different states o f material.  exothermic, endothermic relate to absorption or release of heat from reaction

3) Hydrogen
$Zn (solid) + 2 H Cl$ ⇒ $Zn Cl_2 + H_2 (gas)$