List of practice Questions

The instantaneous voltages at three terminals marked $X , Y$ and $Z$ are given by $V _{ x }= V _{0} \sin \omega t$ $V _{ y }= V _{0} \sin \left(\omega t +\frac{2 \pi}{3}\right)$ and $V _{ z }= V _{0} \sin \left(\omega t +\frac{4 \pi}{3}\right)$ An ideal voltmeter is configured to read $rms$ value of the potential difference between its terminals. It is connected between points $X$ and $Y$ and then between $Y$ and $Z$. The reading(s) of the voltmeter will be

A bird sitting on a single high tension wire does not get electrocuted because

A square loop ABCD, carrying a current I, is placed near and coplanar with a long straight conductor XY carrying a current I, as shown in figure. The net force on the loop will be

For a solution formed by mixing liquids $L$ and $M$, the vapour pressure of $L$ plotted against the mole fraction of $M$ in solution is shown in the following figure. Here $x _{ L }$ and $x _{ M }$ represent mole fractions of $L$ and $M$, respectively, in the solution. The correct statement $(s)$ applicable to this system is (are)

$A\, 6\%$ solution of sucrose $C_{22}H_{22} O_{11}$ is isotonic with $3\%$ solution of an unknown organic substance. The molecular weight of unknown organic substance will be:

The depression in freezing point of $0.1\, M$ aqueous solutions of $HCl$, $CuSO_4$ and $K_2SO_4$ are in the ratio

Azeotropic mixtures are formed only by non-ideal solutions and they may have boiling points either greater than both the components or lesser than both the components. The composition of the vapour phase is same as that of the liquid phase of an azeotropic mixture.

A string has a length of 5m between fixed points and has fundamental frequency of 20 Hz. What is the frequency of the second overtone ?

A spring of force constant $k$ is cut into lengths of ratio $1 : 2 : 3$. They are connected in series and the new force constant is $k'$. Then they are connected in parallel and force constant is $k"$ . Then $k' : k''$ is :

When a simple pendulum is moved from the Earth's surface to deep mine, the period of oscillation

Four massless springs whose force constants are $2k, 2k, k$ and $2k$ respectively are attached to a mass $M$ kept on a frictionless plane as shown in the figure. If the mass $M$ is displaced in the horizontal direction, then the frequency of the system is

For a reaction $\frac{1}{2} A \to 2B$ rate of disappearance of $A$ is related to rate of appearance of $B$ by the expression

In Bryophyta, a specialized organ of the sporophyte for attachment to the gametophyte is called :

In a flask, the weight ratio of $CH _{4}( g )$ and $SO _{2}(g)$ at $298 \,K$ and 1 bar is $1: 2$. The ratio of the number of molecules of $SO _{2}(g)$ and $CH _{4}(g)$ is

Equivalent weight of NH in the reaction, N $?$ NH is 17/3 while that of N is 28/6. Equivalent weight $\quad\quad \quad \quad \quad= \frac{Molecular\, weight}{Number\, of\, e^{-} lost or gained per mole}$

An early model for an atom considered it to have a positively charged point nucleus of charge $Ze$, surrounded by a uniform density of negative charge upto a radius $R$. The atom as a whole is neutral. The electric field at a distance $r$ from the nucleus is $(r < R)$

In a certain region of space, electric field is along the $z$-direction throughout. The magnitude of electric field is however not constant, but increases uniformly along the positive $z$-direction at the rate of $10^5\, N\, C^{-1}\, m^{-1}$. The force experienced by the system having a total dipole moment equal to $10^{-7}\, C\, m$ in the negative $z$- direction is

If $x$ is real number, then $\frac{x}{x^{2}-5 x+9}$ must lie between

IF $f\left(z\right) = \frac{7-z}{1-z^{2}} $ , where $z = 1 + 2i$, then $|f(z)|$ is equal to :

Let $S=\{1,2,3, \ldots \ldots, 9\}$. For $k=1,2, \ldots \ldots, 5$, let $N_{k}$ be the number of subsets of $S$, each containing five elements out of which exactly $k$ are odd. Then $N_{1}+N_{2}+N_{3}+N_{4}+N_{5}=$

A mercury drop of radius $1 \,cm$ is sprayed into $10^{6}$ drops of equal size. The energy expended in joule is (surface tension of mercury is $460 \times 10^{-3}\,N / m$ ):

The colour of the $X_2$ molecules of group $17$ elements changes gradually from yellow to violet down the group. This is due to

$ n $ identical capacitors are joined in parallel and charged to a potential $ V $ . The charged capacitors are disconnected and then connected in series using insulating handles such that the positive plate of one is connected to the negative plate of the other. The potential difference across the free plates of the combination is

Which of the following is an electrophile ?

Which of the following is an electrophile?