Which of the following gates will have an output of $1$?

The half-life of $Ra^{226}$ is $1620$ years. Calculate the number of atoms that decay in one second in $1 \ g$ of radium (Avogadro number $= 6.023 \times 10^{23}$).

If $m_1$ and $m_2$ $(m_1 > m_2)$ are the slopes of the lines represented by $5x^2 - 8xy + 3y^2 = 0$,then $m_1 : m_2$ equals

$I$. Two non-zero,non-collinear vectors are linearly independent.
$II$. Any three coplanar vectors are linearly dependent.
Which of the above statements is/are true?

Which of the following processes can be used to obtain heavy water $(D_2O)$?

Consider the statements given below regarding contraception and answer as directed thereafter:
$(1)$ Medical Termination of Pregnancy $(MTP)$ during the first trimester is generally safe.
$(2)$ Generally,chances of conception are nil until the mother breast-feeds the infant up to two years.
$(3)$ Intrauterine devices like Copper-$T$ are effective contraceptives.
$(4)$ Contraception pills may be taken up to one week after coitus to prevent conception.
Which two of the above statements are correct?