A system performs mechanical work equal to 15 kJ and looses 2 kJ of heat to surrounding. What is the change in internal energy of a system?

What is the designation of an orbital with quantum numbers $\mathrm{n}=4$ and $l=3$?

Which among the following properties is NOT exhibited by transition elements?

For reaction $\mathrm{A}+\mathrm{B} \rightarrow$ product, rate of reaction is $3.6 \times 10^{-2} \mathrm{sec}^{-1}$. When $[\mathrm{A}]=0.2 \mathrm{moldm}^{-3}$ and $[B]=0.1 \mathrm{moldm}^{-3}$, calculate rate constant of reaction if reaction is first order in A and second order is B ?