$540\, g$ of ice at $0\,^{\circ}C$ is mixed with $540\, g$ of water at $80\,^{\circ}C$. The final temperature of the mixture is:

$A$ block of $200 \text{ g}$ mass moves with a uniform speed in a horizontal circular groove with vertical side walls of radius $20 \text{ cm}$. If the block takes $40 \text{ s}$ to complete one round,the normal force exerted by the side walls of the groove is:

Which of the following is the most effective in causing the coagulation of a ferric hydroxide sol?

Which one of the following elements,when present as an impurity in silicon,makes it a $p$-type semiconductor?

If $3p^2 = 5p + 2$ and $3q^2 = 5q + 2$ where $p \neq q$,then the equation whose roots are $3p - 2q$ and $3q - 2p$ is:

Which of the following inhibits the enzyme acetylcholinesterase?