Question 1 :
A bullet of mass 10 g travelling horizontally with a velocity of 150 m/s strikes a stationary wooden block and comes to rest in 0.03 s. What is the magnitude of the force exerted by the wooden block on the bullet?

Question 2 :
A passenger in a moving train tosses a coin which falls behind him. It means that motion of the train is

Question 3 :
Which of the following has more inertia, a five rupes coin or a one rupee coin?

Question 4 :
A hockey ball of mass 200 g travelling at 10 m/s is struck by a hockey stick so as to return it along its original path with a velocity at 5 m/s. What is the magnitude of change of momentum occurred in the motion of the hockey ball by the force applied by the hockey stick?

Question 5 :
A force of 5 N produces an acceleration of 8 $ms^{-2}$ on a mass $m_1$ and an acceleration of 24 $ms^{-2}$ on a mass $m_2$. What acceleration would the same force provide if both the masses are tied together?

Question 6 :
Two friends on roller-skates are standing 5 m apart facing each other. One of them throws a ball of 2 kg towards the other, what will be the net force of person who catches it?

Question 7 :
From a rifle of mass 4 kg, a bullet of mass 50 g is fired with an initial velocity of 35 m/s. What is the initial recoil velociy of the rifle?

Question 8 :
A motorcar of mass 1200 kg is moving along a straight line with a uniform velocity of 90 km/h. lts velocity is slowed down to 18 km/h in 4 s by an unbalanced external force. What is the magnitude of the force required?

Question 9 :
An object of mass 100 kg is accelerated uniformly from a velocity of 5 m/s to 8 m/s in 6s. What is the magnitude of the force exerted on the object?

Question 10 :
<img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2e3f59b460d7261f64d.jpg' /> The above image is the distance-time table of an object in motion. What conclusion can you draw about the acceleration? Is it constant, increasing, decreasing, or zero?

Question 11 :
Determine the number of protons and neutrons for the radioactive atom $^{99}{T}_{c}$.

Question 13 :
The atomic number of the atom which becomes stable by gaining 3 electrons in 5th shell is&#160;:

Question 14 :
Substance $X$ has three common isotopes: $X-48, X-49$ and $X-51$. If the relative abundances of these three isotopes are $42$%, $38$% and $20$% respectively, what is the atomic mass of substance $X$?<br/>

Question 16 :
The $O^{18}/O^{16}$ ratio in some meteorites is greater than the used to calculate the average atomic mass of oxygen one earth. The average mass of an atom of oxygen in these meteorites is ______ that of terrestrial oxygen atom?

Question 17 :
Statement 1: The value of Avogadro's constant is $6.022\times {10}^{23}$<br/>Statement 2: Mole is the ratio of number of atoms present in the substance to the Avogadro number.<br/>Now choose the correct option :

Question 18 :
When a gold sheet is bombarded by a beam of $\alpha$-particles, only a few of them get deflected whereas most go straight, undeflected because:<br/>

Question 19 :
In Millikan's oil drop experiment, the charge of three oil drops X, Y, and Z have been found to be 2, 0.04 and 0.8 respectively. What could be the probable charge of an electron and the number of electrons attached to these oil drops?

Question 20 :
Multiple Answer Question&#160;<br/>According to Bohr, when electron jumps from one shell to another:

Question 21 :
Match the column- I with Column - II and select the correct answer:<br/><table class="wysiwyg-table"><tbody><tr><td>Column - I</td><td>Column -II</td></tr><tr><td>(I) Curie</td><td>A. $10^6 \, dis \, sec^{-1}$</td></tr><tr><td>(II) Rutherford</td><td>B. $3.7 \times 10^{10} \, dis\, sec^{-1}$</td></tr><tr><td>(III) Becquerel</td><td>C. 1 dis $sec^{-1}$</td></tr></tbody></table>

Question 22 :
If one were to apply Bohr's model to a particle of mass 'm' and charge 'q' moving in a plane under the influence of a magnetic field 'B', the energy of the charged particles in the $n^{th}$ level will be:

Question 23 :
If $r_0$ be the radius of first Bohr's orbit of $H-$atom, then the de-Broglie's wavelength of an electron revolving in the third Bohr's orbit will be:

Question 24 :
The formation of the oxide ion, O$^{2-}_{(g)}$, from oxygen atom requires first an exothermic and then an endothermic step as shown below:<br/>$O_{(g)} + e^{-} \rightarrow O^{-}_{(g)}; \Delta H^{\circ} = -141 kJ mol^{-1}$<br/>$O_{(g)}^{-} + e^{-} \rightarrow O^{2-}_{(g)}; \Delta H^{\circ} = +780 kJ mol^{-1}$<br/>Thus, process of formation of $O^{2-}$ in gas phase is unfavourable even though $O^{2-}$ is isoelectronic with neon. It is due to the fact that: