List of practice Questions

An element with mass number $81$ contains $31.7\%$ more neutrons as compared to protons. Find the symbol of the atom
An element X decays first by positron emission and then two ?-particles are emitted in successive radioactive decay. If the product nucleus has mass number 227 and atomic number 89, the mass number and atomic number of element X are
An element $X$ has atomic number $19$. What will be the formula of its oxide?
An elevator which can carry a maximum load of $ 1800 \,kg $ (elevator + passengers) is moving up with a constant speed of $ 2\, ms^{-1} $ . The frictional force opposing the motion is $ 4000\, N $ . What is minimum power delivered by the motor to the elevator?
An element in +3 oxidation state has the electronic configuration (Ar) $3d^3$. Its atomic number is
An element of group $14$ forms two oxides one of which is highly poisonous and neutral. Other oxide can be easily liquefied and compressed to give a solid which is used as a refrigerant under the name of drikold. The element and the oxides are
An element $'P'$ has atomic number $56$. What will be the formula of its halide?
An electron is revolving in the $n^{th}$ orbit of radius $4.2 ?$, then the value of $n$ is $(r_1 = 0.529 ? )$
An electron starts from rest and travels 0.9 m in an electric field of 200 V/m. After this, it enters a magnetic field at right angles to its direction of motion If the radius of circular path of the electron is 9 cm, the magnetic field induction is ($Given\, e=1.6 \times 10^{-19}C, m=9\times 10^{-31}$ kg)
An element crystallises in a structure having a $fcc$ unit cell of an edge $200\,pm$. If $200\,g$ of this element contains $24 \times 10^{23}$ atoms then its density is
An electron is projected with uniform velocity along the axis of a current carrying long solenoid. Which of the following is true?
An electron is revolving around a proton in a circular path of diameter 0.1 nm. It produces a magnetic field $14\,Wb\,m^{-2}$ at the proton. The angular speed of the electron is
An electron and a proton are detected in a cosmic ray experiment, the first with kinetic energy $10 \,keV$, and the second with $100 \,keV$. The ratio of their speeds is (where $m_e$ and $m_p$ are masses of electron and proton respectively)
An electron is in one of the $3d$-orbitals. What are the possible values of $n$, $l$ and $m$ for this electron?
An electrolytic cell contains a solution of $Ag_2SO_4$ and have platinum electrodes. A current is passed until 1.6 gm of $O_2$ has been liberated at anode. The amount of silver deposited at cathode would be
An electromagnetic wave can be produced, when charge is
An Electric field can deflect
An electric current is passed through silver voltameter connected to a water voltmeter. The cathode of the silver voltameter is 0.108 g moreat the end of the electrolysis. The volume ofoxygen evolved at STP is :
An automobile engine develops $100 \,kW$ power when rotating at a speed of $1800\, rpm$. The torque delivered by the engine is
An automobile travelling at $50\, kmh^{-1}$, can be stopped at a distance of 40 m by applying brakes. If the same automobile is travelling at 90 $kmh^{-1}$, all other conditions remaining same and assuming no skidding, the minimum stopping distance in metre is
An edge of a variable cube is increasing at the rate of 10cm/sec. How fast the volume of the cube will increase when the edge is 5 cm long ?
An efficient root inducing chemical useful in Horticulture is
An asteroid of mass m is approaching earth, initially at a distance of 10$R_e$, with speed $v_i$. It hits the earth with a speed $v_f$ ($R_e$ and $M_e$ are radius and mass of earth), then
An asymmetric flower is
An athlete completes one round of a circular track of radius $10\, m$ in $40 \,s$. The distance covered by him in $2$ minutes $20$ seconds is