Mercury thermometer can be used to measure temperature from  - `30^circ C` to `357^circC`.

`because `       acceleration =`a = (v - u)/(t)`

or        `a = (v - v_0)/(t)`

or        `g = (v - v_0)/(t)`                          (considered average force)

`because                    v = 0`

speed before first bounce

     `v_0 `= 5 m/sec`(uarr)`

`:.`   t = `(v - v_0)/(g) = (0 - (-5))/(10) =  5/10 = 0.5 sec`

From the law of pressure ` prop` T

or`P_1/P_2 = T_1/T_2`

or  `P_1/T_1 = P_2/T_2`

Here `P_1 = P,  T_1 = T` 

        ` P_1 = P + 0.4% ,   P = 1.004 P`

       `  T_2 = T  + 1`

`:.`   `   P/T = (1.004 P)/(T + 1)`

or   ` T + 1 = 1.004 T`

or      0.004 T = 1

or  T = `250^circ C`

when spring is massless . Then according to momentum conservation principle,

           ` vec (p_i) = vec(p_f)`

or      `R`      ``right`      `yes` 

in the case of projectile motion, if bodies are projected with same speed , they reaches at ground with same speeds . So  if bodies have same msse3s then momentum of body will be different for different directions of projection  but magnitude of moments must be same .

Since , no external force is present on the system . So conservation principle of momentum is applicable .

`:.`           `vec(p_i) = vec(p_f) = vec (p_1) + vec(p_2)`

`:.`          ` vec (p_1) = - vec (p_2)`                                               (  `because    vec (p_i) = 0)`

`:.`         l`vec(p_1)`l =  l - `vec(p_2)`l

`:.`       `vec(p_1) = vec(p_2)`

From this point of view, it is clear that moments of both  particles are equal in magnitude but opposite in direction .

Also friction is absent . So total mechanical energy of system remains conserved .

Since , no external force is present. So momentum conservation principle is completely applicable

`:.`        `m vec(n) = m_1 vec(n_1) + m_2 vec(n_2)`

or `(m_1 + m_2) vec(n) = m_1 vec(n_1) + m_2 vec(n_2)`

Hence , (d) is correct .

(A) During firing of the bullet from gun , the chemical energy of powder of bullet is converted into the kinetic of the system . So, final mechanical energy of system is greater than initial kinetic energy of the sysem.

(B) In this case chemical energy (non-mechanical) is converted into  mechanical energy of the system.

(C) The same reason as the above.

(D) The same reason as (A) and (B).