The decay of $_{92}U^{235}$ is a reaction of .......... order.

Radium has an atomic weight of $226$ and a half-life of $1600$ years. The number of disintegrations produced per second from $1 \ g$ of radium is:

An element has a half-life of $1600 \ years$. The fraction of the mass left after $6400 \ years$ will be:

If the amount of radioactive substance is increased three times,the number of atoms disintegrated per unit time would

$A$ radioactive sample has a half-life of $1500 \ years$. $A$ sealed tube containing $1 \ g$ of the sample will contain after $3000 \ years$:

$A$ piece of wood from an archaeological sample has $5.0 \text{ counts min}^{-1} \text{ g}^{-1}$ of $^{14}C$,while a fresh sample of wood has a count of $15.0 \text{ counts min}^{-1} \text{ g}^{-1}$. If the half-life of $^{14}C$ is $5770 \text{ yr}$,the age of the archaeological sample is: