Which gases are released when aluminum reacts with concentrated $HCl$ and concentrated $NaOH$ respectively?

$A$ body of mass $m = 10^{-2} \; kg$ is moving in a medium and experiences a frictional force $F = -kv^2$. Its initial speed is $v_0 = 10 \; m/s$. If,after $10 \; s$,its energy is $\frac{1}{8} mv_0^2$,the value of $k$ will be:

The electric current $i$ in the circuit shown is (in $A$)

$A$ metal ball of mass $2 \ kg$ moving with a velocity of $36 \ km/h$ has a head-on collision with a stationary ball of mass $3 \ kg$. After the collision,if both balls move together,the loss in kinetic energy due to the collision is: (in $J$)

$\int_0^3 \frac{3x+1}{x^2+9} dx$ is equal to :

$A$ particle of mass $m$ and charge $q$ is placed at rest in a uniform electric field $E$ and then released. The kinetic energy attained by the particle after moving a distance $y$ is