Question

please answer my questions​

Answer 1

Answer for Question No 12

a) The above activity proves that water kept in a container exerts pressure on the walls of the container.

Brief Explanation - Any Liquid kept inside a container exerts some pressure due to it's own weight (effect of gravity) on the walls of the container in which it is kept. This pressure is directly proportional to height, density and acceleration due to gravity . Now when drilled in the container, water flows out of the container due to the pressure energy stored and hence gain certain velocity.

b) Given Force = 600N

  Given Area = 20 $m^{2}$

Pressure = $\frac{Given Force}{ Area In Contact}$ = $\frac{600}{20}$= 30N$m^{-2}$

c) Walls of the dams are thicker in the bottom than at the top because the water falling from the top on the bottom the dam exerts greater pressure due to its increase in kinetic energy.

Brief Explanation - Whenever there is a huge change in velocity and Kinetic energy a large amount of force is also produced due to it. This Force is exerted on the bottom of the dam. To reduce the pressure and prevent the damage the walls are made thick.

Answer of Question No 13

a) Bright yellow-orange flame.

b) $2Mg(s) + O_{2} (g) = 2MgO(s)$

c) Magnesium Hydroxide ($Mg(OH)_{2}$)

d) Red Litmus turns blue, Blue litmus remains same.

e) Conclusion- Metal Hydroxides are generally Basic. Also Metals give characteristic flame color. Metal Hydroxides are formed by mixing oxides in presence of water.