If the \(\mathrm{pH}\) of \(0.10 \mathrm{M}\) monobasic acid at \(298 \mathrm{~K}\) is 5.0, the value of \(\mathrm{p} K_a\) at the same temperature is

Which one of the following is correct?

One per cent composition of an organic compound \(A\) is, carbon : \(85.71 \%\) and hydrogen \(14.29 \%\). Its vapour density is 14 . Consider the following reaction sequence


Identify \(\underline{C}\),

Which of the following are non-metal displacement reactions?
(A) \(\mathrm{Ca}(s)+2 \mathrm{H}_2 \mathrm{O}(l) \longrightarrow \mathrm{Ca}(\mathrm{OH})_2(a q)+\mathrm{H}_2(g)\)
(B) \(\mathrm{V}_2 \mathrm{O}_5(s)+5 \mathrm{Ca}(s) \stackrel{\Delta}{\longrightarrow} 2 \mathrm{~V}(s)+5 \mathrm{CaO}(s)\)
(C) \(2 \mathrm{Fe}(s)+3 \mathrm{H}_2 \mathrm{O}(l) \stackrel{\Delta}{\longrightarrow} \mathrm{Fe}_2 \mathrm{O}_3(s)+3 \mathrm{H}_2(g)\)
(D) \(\mathrm{Cr}_2 \mathrm{O}_3(s)+2 \mathrm{Al}(s) \stackrel{\Delta}{\longrightarrow} \mathrm{Al}_2 \mathrm{O}_3(s)+2 \mathrm{Cr}(s)\)

For a reversible reaction, if the concentration of the reactants is reduced to half, the equilibrium constant will be.........

Which of the following reactions give phosphine?
(i) Reaction of calcium phosphide with water
(ii) Heating white phosphorous with concentrated NaOH solution in inert atmosphere
(iii) Heating red phosphorous with alkali

Which among the following oxides is the most basic?

\(\overrightarrow{\mathbf{A}}\) and \(\overrightarrow{\mathbf{B}}\) are two vectors of equal magnitudes and \(\theta\) is the angle between them. The angle between \(\overrightarrow{\mathbf{A}}\) or \(\overrightarrow{\mathbf{B}}\) with their resultant is

Which reaction(s) among the following produce dinitrogen?

In the triangle with vertices at \(A(6,3), B(-6,3)\) and \(C(-6,-3)\), the median through \(A\) meets
\(B C\) at \(P\), the line \(A C\) meets the \(x\)-axis at \(Q\), while \(R\) and \(S\) respectively denote the orthocentre and centroid of the triangle. Then the correct matching of the coordinates of points in List-I to List-II is
\(\begin{array}{llll} & \text { List-I } & & \text { List-II } \\ \text { (i) } & P & \text { (A) } & (0,0) \\ \text { (ii) } & Q & \text { (B) } & (6,0) \\ \text { (iii) } & R & \text { (C) } & (-2,1) \\ \text { (iv) } & S & \text { (D) }(-6,0) \\ & & \text { (E) }(-6,-3) \\ & & \text { (F) }(-6,3)\end{array}\)
(i)
(ii)
(iii)
(iv)

A radioactive element \(X\) converts into another stable element \(Y\). Half life of \(X\) is 2 hours. Initially only \(X\) is present. After a time \(t\), if the ratio of atoms of \(X\) to \(Y\) is \(1: 4\), then the value of \(t\) is

A capacitor of capacitance $C_1=1 \mu \mathrm{F}$ is charged using a $9 \mathrm{V}$ battery. $C_1$ is then removed from the battery & connected to capacitors $C_2$ and $C_3$ of $2 \mu \mathrm{F}$ and $3 \mu \mathrm{F}$ respectively as shown in the figure. Find the charge on $C_3$ after equilibrium has reached is

Which of the following complexes formed by Nickel is tetrahedral and paramagnetic?