Answer: Option A. -> Both pointing into the plane.
:
A
Applying Fleming’s left hand rule, holding the forefinger, middle finger, and thumb of the left hand in mutually perpendicular directions, the forefinger indicates the direction of the magnetic field and the middle finger, the direction of the current, then the thumb will indicate the direction of the force on a charge. The direction of current is always opposite to the direction of flow of electrons. With help of Fleming’s left hand rule, we can infer that the force is acting into the plane.

Answer: Option B. -> Increasing the current in the conductor.
:
B and C

We know that, force on a current carrying conductor placed in a magnetic field is $F$ = $Bil$. Given, the direction of electric current is perpendicular to the magnetic field.
So, amount of force experienced by a current carrying conductor placed in a magnetic field depends on
(i) the current in the conductor $\left(i\right)$
(ii) the strength of the magnetic field $\left(B\right)$.
(iii) length of the conducting wire $\left(l\right)$.

Answer: Option A. -> the number of coil turns per unit length
:
A and B
The strength of the magnetic field generated by a solenoid can be increased by:
(i) Increasing the number of turns per unit length. The more the number of turns in a solenoid, the stronger is the magnetic field produced.
(ii) Increasing the electric current. The larger the current passed through the solenoid, the stronger is the magnetic field produced. 
(iii) The nature of the core material used. Using soft iron as the core in the solenoid, increases the magnetic field strength.
However, the field strength does not depend on the mass or the density of the coil material.

Answer: Option A. -> True
:
A
The magnetic field produced by a current-carrying solenoid is similar to the magnetic field produced by a bar magnet. The magnetic field lines inside a solenoid is straight and equally spaced. This indicates that the strength of the magnetic field inside a solenoid is the same at all the points.

Answer: Option A. -> Soft iron
:
A

The soft iron inside the coil makes the magnetic field stronger because it becomes a magnet itself when the current is flowing through it.
Also, this material does not retain the magnetism when the current flow is stopped. This property of soft iron is much desirable for electromagnets.

Answer: Option A. -> If the material of the core of electromagnet is changed.
:
A, B, and D

The strength of the magnetic field between the poles of an electromagnet depends on:

The number of turns in the coil. If we increase the number of turns in the coil, the strength of electromagnet increases.

The current flowing in the coil. If the current in the coil is increased, the strength of electromagnet increases.

The material of the core. The strength of the magnetic field increases if the air core is replaced by soft iron. i.e. the strength of the magnetic field depends on the material of the core. 

Changing the direction of current in electromagnet just changes the direction of the magnetic field. Its strength remains unaffected.

Answer: Option C. -> 2 north,2 south
:
C

If one magnet is broken into two, we always get two separate smaller magnets. Both the magnets will have their own North and the South Pole. Hence when the above magnet is broken in the middle, we get 4 poles; 2 north poles and 2 south poles.

Answer: Option A. -> They do not intersect.
:
A

The magnetic field lines indicate the direction of magnetic field at a point. If they intersect at a point, there would be more than one direction of magnetic field which is practically not possible.

Answer: Option A. -> True
:
A

A magnetic field is developed around a current carrying conductor. The magnetic needle is deflected as a result of the interaction of this magnetic field and that around the magnetic needle. Thus, the given statement is true.

Answer: Option B. -> It will be reversed.
:
B
A current carrying conductor placed in a magnetic field experiences a force if the current and magnetic field are mutually perpendicular. The direction of this force can be found out with the help of Fleming's Left Hand Rule. However, if the direction of the current in the conductor is reversed, then the direction of the force acting on it also gets reversed, i.e. the direction of force changes by ${180}^{\circ }.$