Which of the following is a wrong statement?

$A$ square coil $ABCD$ lies in the $x-y$ plane with its centre at the origin. $A$ long straight wire passing through the origin carries a current $i = 2t$ in the negative $z$-direction. The induced current in the coil is

$A$ part of a complete circuit is shown in the figure. At some instant,the value of current $I$ is $1\, A$ and it is decreasing at a rate of $10^{2}\, A s^{-1}$. The value of the potential difference $V_{P} - V_{Q}$ (in volts) at that instant is:

$A$ metallic square wire loop of side $10\, cm$ and resistance $1\,\Omega$ is moved with a constant velocity $v_0$ in a uniform magnetic field of induction $B = 2\, T$ as shown in the figure. The magnetic field is perpendicular into the plane of the loop. The loop is connected to a network of resistors each of value $3\,\Omega$. The resistance of the lead wires $OS$ and $PQ$ are negligible. What should be the speed of the loop so as to have a steady current of $1\, mA$ in it? Give the direction of current in the loop.

$A$ conducting loop in the shape of a right-angled isosceles triangle of height $10 \ cm$ is kept such that the $90^{\circ}$ vertex is very close to an infinitely long conducting wire (see the figure). The wire is electrically insulated from the loop. The hypotenuse of the triangle is parallel to the wire. The current in the triangular loop is in counterclockwise direction and increases at a constant rate of $10 \ As^{-1}$. Which of the following statement$(s)$ is(are) true?
$(A)$ The magnitude of induced emf in the wire is $\left(\frac{\mu_0}{\pi}\right) \ V$
$(B)$ If the loop is rotated at a constant angular speed about the wire,an additional emf of $\left(\frac{\mu_0}{\pi}\right) \ V$ is induced in the wire
$(C)$ The induced current in the wire is in the opposite direction to the current along the hypotenuse
$(D)$ There is a repulsive force between the wire and the loop

$A$ coil and a bulb are connected in series with a $DC$ source. $A$ soft iron core is then inserted into the coil. What happens to the intensity of the bulb?