MCQ
A radioactive material decays by simultaneous emission of two particles with respective half lives 1620 and 810 years. The time (in years) after which one- fourth of the material remains is
- ✓1080
- B2430
- C3240
- D4860
✓
Answer
Correct option: A.
1080
(a) 1080
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Three plates of common surface area $A$ are connected as shown. The effective capacitance will be
→The electric and the magnetic field, associated with an e.m. wave, propagating along the $+\, z-$axis, can be represented by
→Two batteries one of the $\mathrm{emf}$ $3\,V$, internal resistance $1$ ohm and the other of $\mathrm{emf}$ $15\, V$, internal resistance $2$ $\mathrm{ohm}$ are connected in series with a resistance $R$ as shown. If the potential difference between $a$ and $b$ is zero the resistance of $R$ in $\mathrm{ohm}$ is
→Due to the flow of current in a circular loop of radius $R$, the magnetic field produced at the centre of the loop is $B$. The magnetic moment of the loop is :-
The north pole of a long horizontal bar magnet is being brought closer to a vertical conducting plane along the perpendicular direction. The direction of the induced current in the conducting plane will be
${H^ + },\,H{e^ + }$ and ${O^{ + + }}$ ions having same kinetic energy pass through a region of space filled with uniform magnetic field $B$ directed perpendicular to the velocity of ions. The masses of the ions ${H^ + },\,H{e^ + }$and ${O^{ + + }}$ are respectively in the ratio $1:4:16$. As a result
→If identical charges $( - q)$ are placed at each corner of a cube of side $b$, then electric potential energy of charge $( + q)$ which is placed at centre of the cube will be
→The $1^{\text {st }}, 2^{\text {nd }}$ and the $3^{\text {Id }}$ ionization enthalpies $I _1, I _2$ and $I _3$, of four atoms with atomic numbers $n , n +1$, $n +2$ and $n +3$, where $n <10$, are tabulated below. What is the value of $n$ ?
→| Atomic number | Ionization Enthalpy ($kJ/mol$) | ||
| $n$ | $l _1$ | $l _2$ | $l _3$ |
| $n +1$ | $1681$ | $3374$ | $6050$ |
| $n +2$ | $2081$ | $3952$ | $6122$ |
| $n +3$ | $496$ | $4562$ | $6910$ |
| $738$ | $1451$ | $7733$ |
he half-life of a radioactive substance is 48 hours. How much time will it take to disintegrate to its $\frac {1}{16}$ th part
→The heat produced by a $100\, watt$ heater in $2$ minute will be equal to
→