The probability of a leap year having $53$ Wednesdays is ...........

$A$ student says that if you throw a die,it will show up $1$ or not $1$. Therefore,the probability of getting $1$ and the probability of getting 'not $1$' each is equal to $\frac{1}{2}$. Is this correct? Give reasons.

Two balanced dice are rolled simultaneously. Then,the probability that the numbers appearing on both the dice are different is ........

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:
$A:$ Exactly $2$ heads are received.

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 $4$?