JEE Main 2018 Question Paper (15-Apr-2018) (Shift 1)

Question 1

The equivalent capacitance between $A$ and $B$ in the circuit is given below.

Accepted Answer

$2.4 \quad \mathrm{\mu F}$

Answer

$3.6 \quad \mathrm{\mu F}$

Answer

$4.9 \, \mu\mathrm{F}$

Answer

$5.4\, \mu\mathrm{F}$

Question 2

A charge $Q$ is placed at a distance $\frac{a}{2}$ above the centre of a square surface of side length $a$. The electric flux through the square surface due to the charge would be?

Accepted Answer

$ \frac{Q}{6 \epsilon_{0}} $

Answer

$ \frac{Q}{2\epsilon_{0}} $

Answer

$ \frac{Q}{3\epsilon_{0}} $

Answer

$ \frac{Q}{\varepsilon_{0}} $

Question 3

A uniform rod $AB$ is suspended from a point $X$, at a variable distance $x$ from $A$, as shown. To make the rod horizontal, a mass $m$ is suspended from its end $A$. A set of $(m, \quad x)$ values is recorded. The appropriate variables that give a straight line, when plotted, are:

Accepted Answer

$ m, \frac{1}{x} $

Answer

$m, x^{2}$

Answer

$ m, \frac{1}{x^{2}} $

Answer

$m, x$

Question 4

The energy required to remove the electron from a singly ionized Helium atom is $2.2$ times the energy required to remove an electron from a Helium atom. The total energy required to ionize the Helium atom completely is close to

Accepted Answer

$79 \quad \mathrm{eV}$

Answer

$34 \quad \mathrm{eV}$

Answer

$20 \quad \mathrm{eV}$

Answer

$109 \quad \mathrm{eV}$

Question 5

A solution containing active cobalt $ {}_{27}^{60}\mathrm{Co} $ having an activity of $ 0.8 \ \mathrm{\mu Ci} $ and decay constant $ \lambda $ is injected in an animal's body. When $ 1 \ \mathrm{cm}^3 $ blood is drawn from the animal's body after $ 10 \ \mathrm{h} $ of injection, the activity was found to be $ 300 \ \mathrm{dpm} $ (decays per minute), then the total volume of blood in the animal's body is close to $ \left[ 1 \ \mathrm{Ci} = 3.7 	imes 10^{10} \ \mathrm{dps} 	ext{ (decays per second) and at } t = 10 \ \mathrm{h}, \ e^{-\lambda t} = 0.84 ight] $

Accepted Answer

$5 \quad \mathrm{L}$

Answer

$4 \quad \mathrm{L}$

Answer

$6 \quad \mathrm{L}$

Answer

$7 \quad \mathrm{L}$