Which of the following is not correctly matched?

The main structural component of a virus is:

The half-life of a radioactive substance against $\alpha$-decay is $1.2 \times 10^7 \ s$. What is the decay rate for $4 \times 10^{15}$ atoms of the substance?

$A$ circular disc is rolling on a horizontal plane. Its total kinetic energy is $300 \ J$. What is its translational kinetic energy?

$A$ horizontal straight wire $20\, m$ long extending from east to west is falling with a speed of $5.0\, m/s$,at right angles to the horizontal component of the earth's magnetic field $0.30 \times 10^{-4}\, Wb/m^2$. The instantaneous value of the $e.m.f.$ induced in the wire will be.....$mV$.

Which organ does not participate in fetal circulation?