The probability of scoring $100$ marks in a question paper of $100$ marks is ................

Two balanced dice are rolled simultaneously. Then,the probability that the sum of the numbers on two dice is a prime number is ............

Two balanced dice are rolled. Find the probability that the sum of numbers on two dice is smaller than $7$.

$A$ balanced die is thrown. Find the probability that the number on the die is a multiple of $3$.

Two unbiased dice are thrown once. Write all the possible outcomes of this experiment. What is the probability that the sum of numbers on two dice is a multiple of $3$ or $4$?

An unbiased coin is tossed thrice. Find the probability of the following event:
$B:$ at least $2$ heads are received.