List of practice Questions

If the mean deviation about the mean is $m$ and the variance is $\sigma^2$ for the following data, then $m + \sigma^2 =$ % Data table \[ \begin{array}{|c|c|c|c|c|c|} \hline x & 1 & 3 & 5 & 7 & 9 \\ \hline f & 4 & 24 & 28 & 16 & 8 \\ \hline \end{array} \]

Choose the correct statements from the following: I) In vapour phase, $ BeCl_2 $ exists as a chlorobridged dimer.
II) $ BeSO_4 $ is readily soluble in water.
III) $ BeO $ is completely basic in nature.
IV) $ BeCO_3 $, being unstable, is kept in the atmosphere of $ CO_2 $.
V) $ BeCO_3 $ is less soluble among all the carbonates of group 2 elements.

Observe the following species: (i) $ NH_3 $ (ii) $ AlCl_3 $ (iii) $ SnCl_4 $ (iv) $ CO_2 $ (v) $ Ag^+ $ (vi) $ HSO_4^- $ How many of the above species act as Lewis acids?

P is a variable point such that the distance of P from A(4,0) is twice the distance of P from B(-4,0). If the line $ 3y - 3x - 20 = 0 $ intersects the locus of P at the points C and D, then the distance between C and D is:

A massless spring of length $ l $ and spring constant $ k $ oscillates with a time period $ T $ when loaded with a mass $ m $. The spring is now cut into three equal parts and connected in parallel. The frequency of oscillation of the combination when it is loaded with a mass $ 4m $ is: \vspace{0.5cm}

In $ \triangle ABC $, if $ AB:BC:CA = 6:4.5 $, then $ R : r = $

The normality of a 20-volume solution of hydrogen peroxide is:

In the given reaction sequence, identify Z.

Reaction of conversion of Y to Z in the given reaction corresponds to:

(a)(i) In the recent past, the Government of India has taken crucial steps, like Jan-Dhan Yojana, for efficient allocation of financial resources.
State and elaborate whether the statement is true or false, with valid arguments.

A solid is dissolved in 1 L water. The enthalpy of its solution ($\Delta H_{{sol}}^\circ$) is 'x' kJ/mol. The hydration enthalpy ($\Delta H_{{hyd}}^\circ$) for the same reaction is 'y' kJ/mol. What is lattice enthalpy ($\Delta H_{{lattice}}^\circ$) of the solid in kJ/mol?

A circular plate of radius $ r $ is removed from a uniform circular plate P of radius $ 4r $ to form a hole. If the distance between the centre of the hole formed and the centre of the plate P is $ 2r $, then the distance of the centre of mass of the remaining portion from the centre of the plate P is?

The region in the output voltage versus input voltage graph where a transistor can be used as an amplifier is?

A thin plano-convex lens of focal length 73.5 cm has a circular aperture of diameter 8.4 cm. If the refractive index of the material of the lens is $ \frac{5}{3} $, then the thickness of the lens is nearly.

When an object of height 12 cm is placed at a distance from a convex lens, an image of height 18 cm is formed on a screen. Without changing the positions of the object and the screen, if the lens is moved towards the screen, another clear image is formed on the screen. The height of this image is.

The difference between the fundamental frequencies of an open pipe and a closed pipe of the same length is 100 Hz. The difference between the frequencies of the second harmonic of the open pipe and the third harmonic of the closed pipe is:

A solid sphere rolls down without slipping from the top of an inclined plane of height 28 m and angle of inclination 30Â°. The velocity of the sphere when it reaches the bottom of the plane is (Acceleration due to gravity $ g = 10 \, \text{m/s}^2 $)

$$ x^5 + 4x^4 - 13x^3 - 52x^2 + 36x + 144 = 0 $$

What is the fate of a piece of DNA carrying only gene of interest which is transfered in to an alien organism?
A. The piece of DNA would be able to multiply itself independently in the progeny cells of the organism.
B. It may get integrated into the genome of the recipient.
C. It may multiple and be inherited along with the host DNA.
D. The alien piece of DNA is not an integral part of chromasame.
E. It shows ability to replicate.
Choose the correct answer from the options given below:

What is 'C' in the given sequence of reactions?

An $\alpha$-particle of energy $ E $ is liberated during the decay of a nucleus of mass number 236. The total energy released in this process is 236. The total energy released in this process is

A body is projected from the ground at an angle of $ \tan^{-1}\sqrt{7} $ with the horizontal. At half of the maximum height, the speed of the body is $ n $ times the speed of projection. The value of $ n $ is

RUBISCO CO acts as

Review:
You have recently read a famous book/magazine. Write a Review on the same with the help of the following points:
- title, front page, back page
- language, features, contents
- Pictures, quality, presentation
- Values, vision and variety

A bob is whirled in a horizontal circle by means of a string at an initial speed of 10 rpm. If the tension in the string is quadrupled while keeping the radius constant, the new speed is: