AIIMS 2018

Assertion (A) \(\mathrm{NaCl}\) reacts with concentrated \(\mathrm{H}_2 \mathrm{SO}_4\) to give colourless fumes with pungent smell. But on adding \(\mathrm{MnO}_2\) the fumes become greenish yellow.
Reason (R) \(\mathrm{MnO}_2\) oxidises $...

In which of the following arrangements, the
order is not strictly according to the property
written against it?

The ionic radii \((\mathop A\limits^o)\) of \(\mathrm{C}^{4-}\) and \(\mathrm{O}^{2-}\) respectively are 2.60 and 1.40. The ionic radius of the isoelectronic ion \(\mathrm{N}^{3-}\) would be

Assertion (A) Electron gain enthalpy
becomes less negative as we go down a group.
Reason (R) Size of the atom increases on
going down the group and the added electron
would be farther away from the nucleus.

In the above reaction sequence, \(X\) is

Assertion (A) The molecular mass of the
polymers cannot be calculated using the
boiling point or freezing point method.
Reason (R) The freezing point method is
used for determining the molecular mass of
small molecules.

Assertion (A) Most of the synthetic
polymers are not biodegradable.
Reason (R) Polymerisation process induces
toxic polymerisation.

Assertion (A) Beryllium carbonate is kept
in the atmosphere of carbon dioxide.
Reason (R) Beryllium carbonate is unstable
and decomposes to give beryllium oxide and
carbon dioxide.

Which of the following is an example of network solid?

Niobium crystallises in body centred cubic structure. If density is \(8.55 \mathrm{~g} \mathrm{~cm}^{-3}\), then the atomic radius of niobium is (atomic mass of niobium \(=93 u\) )

A solid has a structure in which W atoms are
located at the corners of a cubic lattice.
O atoms at the centre of edges and Na atom
at centre of the cube. The formula for the
compound is

Assertion (A) Graphite is an example of tetragonal crystal system.
Reason (R) For a tetragonal system, \(a=b \neq c\) and \(\alpha=\beta=90^{\circ}, \gamma=120^{\circ}\).

Benzoic acid undergoes dimerisation in benzene solution. The van't Hoff factor \((i)\) is related to the degree of association '\(x\)' of the acid as

The correct order of decreasing stability of
the following carbocation is

The correct IUPAC name of the given compound is

The work function of a metal is \(4.2 \mathrm{~eV}\). If radiation of 2000 \(\mathop A\limits^o\) fall on the metal then the kinetic energy of the fastest photoelectron is

When an excess and a very dilute aqueous
solution of KI is added to very dilute
aqueous solution of silver nitrate. The
colloidal particles of silver iodide which are
associated with the Helmholtz double layer
in the form of

Assertion (A) Micelles are formed by
surfactant molecules above the critical
micellar concentration (CMC).
Reason (R) The conductivity of a solution
having surfactant molecules decreases
sharply at the CMC.

In an adiabatic process, no transfer of heat
takes place between system and
surroundings. Choose the correct option for
free expansion of an ideal gas under
adiabatic condition from the following

\(\Delta H\) and \(\Delta E\) for the reaction,
\(\mathrm{Fe}_2 \mathrm{O}_3(s)+3 \mathrm{H}_2(g) \longrightarrow 2 \mathrm{Fe}(s)+\mathrm{H}_2 \mathrm{O}(l)\)
at constant temperature are related as

In a series R-C circuit shown in figure, the
applied voltage is 10 V and the voltage across
capacitor is found to be 8V. Then, the voltage
across R and the phase difference between
current and the applied voltage will
respectively be

An ideal coil of \(10 \mathrm{~H}\) is connected in series with a resistance of \(5 \Omega\) and a battery of \(5 \mathrm{~V}\). After \(2 \mathrm{~s}\), after the connection is made, the current flowing (in ampere) in the circuit is

In a circuit \(L, C\) and \(R\) are connected in series with an alternating voltage source of frequency \(f\). The current leads the voltage by \(45^{\circ}\). The value of \(C\) is

The half-life of a radioactive substance is \(20 \mathrm{~min}\). The approximate time interval \(\left(t_2-t_1\right)\) between the time \(t_2\), when \(\frac{2}{3}\) of it has decayed and time \(t_1\) when \(\frac{1}{3}\) of it had decaye...

Assertion If electrons in an atom were
stationary, then they would fall into the
nucleus.
Reason Electrostatic force of attraction acts
between negatively charged electrons and
positive nucleus.

Assertion Radioactive nuclei emits \(\beta^{-}\)-particles.
Reason Electrons exist inside the nucleus.

An infinite number of identical capacitors
each of capacitance 1 \(\mu\)F are connected as
shown in the figure. Then, the equivalent
capacitance between A and B is

Assertion A dielectric slab is inserted
between plates of an isolated charged
capacitor which remain same.
Reason Charge on an isolated system is
conserved.

Body of mass M is much heavier than the
other body of mass m. The heavier body with
speed v collides with the lighter body which
was at rest initially elastically. The speed of
lighter body after collision is

Three bodies having masses \(5 \mathrm{~kg}, 4 \mathrm{~kg}\) and \(2 \mathrm{~kg}\) is moving at the speed of \(5 \mathrm{~m} / \mathrm{s}, 4 \mathrm{~m} / \mathrm{s}\) and \(2 \mathrm{~m} / \mathrm{s}\) respectively along \(X\)-axis. The ...

Assertion Two particles moving in the same
direction do not lose all their energy in
completely inelastic collision.
Reason Principle of conservation of
momentum holds true for all kinds of
collisions.

A diode detector is used to detect and
amplitude modulated wave of 60%
modulation by using a condenser of capacity
250 pF in parallel with a load resistance
100 k\(\Omega\). Find the maximum modulated
frequency which could be detected by it...

A metal wire has a resistance of \(35 \Omega\). If its length is increased to double by drawing it, then its new resistance will be

In the circuit in the figure, if no current
flows through the galvanometer when the
key K is closed, the bridge is balanced. The
balancing condition for bridge is

In the circuit, shown the galvanometer \(G\) of resistance \(60 \Omega\) is shunted by a resistance \(r=0.02 \Omega\). The current through \(R\) is nearly \(1 \mathrm{~A}\). The value of resistance \(R\) (in ohm) is nearly

In the adjoining circuit diagram, the
readings of ammeter and voltmeter are 2 A
and 120 V, respectively. If the value of R is
75\(\Omega\), then the voltmeter resistance will be

Assertion Terminal voltage of a cell is greater
than emf of cell during charging of the cell.
Reason The emf of a cell is always greater
than its terminal voltage.

Assertion Bulb generally get fused when
they are switched on or off.
Reason When we switch on or off, a circuit
current changes in it rapidly.

The graph between the energy log E of an
electron and its de-Broglie wavelength log \(\lambda\) will be

A system \(S\) consists of two coils \(A\) and \(B\). The coil \(A\) carries a steady current \(I\). While the coil \(B\) is suspended nearby as shown in figure. Now, if the system is heated, so as to raise the temperature of two coils stea...

A circular loop of radius 0.3 cm lies parallel
to a much bigger circular loop of radius 20 cm.
The centre of the small loop on the axis of
the bigger loop. The distance between their
centres is 15 cm. If a current of 20 A flows
through the ...

A half ring of radius \(R\) has a charge of \(\lambda\) per unit length. The electric force on \(1 \mathrm{C}\) charged placed at the centre is

Positive charge \(Q\) is distributed uniformly over a circular ring of radius \(R\). A point particle having a mass \((m)\) and a negative charge \(-q\) is placed on its axis at a distance \(x\) from the centre. Assuming \(x < R\), find the...

Assertion Mass of a body decreases slightly
when it is negatively charged.
Reason Charging is due to transfer of electrons.

Assertion A convex mirror always make a
virtual image.
Reason The ray always diverge after
reflection from the convex mirror.

Two satellites \(A\) and \(B\) revolve round the same planet in coplanar circular orbits lying in the same plane. Their periods of revolutions are \(1 \mathrm{~h}\) and \(8 \mathrm{~h}\), respectively. The radius of the orbit of \(A\) is $$...

A planet is revolving around the sun in a circular orbit with a radius \(r\). The time period is \(T\). If the force between the planet and star is proportional to \(r^{-3 / 2}\), then the square of time period is proportional to

The weight of a body on the surface of the
earth is 63 N. What is the gravitational force
on it due to the earth at a height equal to
half the radius of the earth?

An ideal gas of mass \(m\) in a state \(A\) goes to another state \(B\) via three different processes as shown in figure. If \(Q_1, Q_2\) and \(Q_3\) denote the heat absorbed by the gas along the three paths, then

A gas consisting of a rigid diatomic molecules
was initially under standard condition. Then,
gas was compressed adiabatically to
one-fifth of its initial volume. What will be
the mean kinetic energy of a rotating
molecule in the final state...