Answer: Option A. -> Fuse wire
:
A
A fuse is a short length of wire designed to break the circuit in case of excessive current. Temperature increases with current, and after a point the fuse melts thereby breaking the circuit. Fuse wire is made up of a material which has low melting point, thereby saving electrical applicances from damage.

Answer: Option A. -> ISI mark
:
A
The government of India has created some standards for almost every product to protect the economic interests of all citizens. These standards are like AGMARK for agricultural products, ISI mark for electric products, BIS mark for gold ornaments and FPO mark for all the processed fruit products. It is advised to use electrical appliances and gadgets, which are electricity efficient. ISI mark is an assurance of conformity to the specifications given on the products. It is therefore suggested to use ISI mark products.

Answer: Option C. -> negatively charged
:
C

Electrons are the negatively charged particles of an atom. The negative charge of electrons in the orbitals of an atom balances the positive charge of the protons in the atomic nucleus. They are extremely small compared to all the other parts of the atom. The mass of an electron is almost $1837$ times less than the mass of a proton.

Answer: Option C. -> negatively charged
:

Each part: 1 Mark
(a) For changing the direction in which magnetic needle gets deflected, we have to reverse the direction of current flowing in the wire. This can be achieved by changing the polarity of the battery.
(b) Magnetic field lines give the direction of magnetic field around a conductor. So the pattern of field lines is similar to that of iron fillings, i.e. concentric circles. The figure below shows the magnetic field lines around a current carrying conductor.

Answer: Option C. -> negatively charged
:

An ammeter is used to measure electric current in an electric circuit.

Answer: Option C. -> negatively charged
:
Explanation: 2 Marks
Diagram: 1 Mark
In the given circuit, the positive terminals of both the batteries are joined together so there is no flow of current and hence the bulb didn't glow.
The current flows from positive terminals, therefore, the positive terminals of the cell will be connected to negative terminal of the cell and vice versa.
Current always flows from the positive terminal to the negative terminal.

Answer: Option C. -> negatively charged
:
Fuses: 1.5 Marks
Alternative: 0.5 Marks
Electrical fuses are wires made from special materials that melt quickly and break when large electric current is passed through them.
There is a maximum limit of current which can safely pass through the circuit. 
When a large amount of current passes through the circuit it may cause damage to various electric appliances.
The appliances may also catch fire due to short-circuit. 
So, fuses are used for safety purposes.
MCBs can be used instead of fuses.
 

Answer: Option C. -> negatively charged
:

Each question: 2 Marks
An electromagnet is a type of magnet in which the magnetic field is produced by an electric current. The magnetic field disappears when the current is turned off. A current-carrying coil or an insulated wire wrapped around a piece of iron behaves like an electromagnet.
Two methods by which we can increase the strength of magnetic field are:
1) By increasing the number of turns of wire in the coil.
2) By increasing the current flowing in the coil.

Answer: Option C. -> negatively charged
:

Explanation: 2 Marks
The magnetic field at any point can be in one direction only. If two magnetic lines of force intersect each other, at the point of intersection there will be two different directions of the magnetic field, which is not possible.

Answer: Option C. -> negatively charged
:

Reason: 2 Marks
Preventive measure: 1 Mark
The various reasons due to which there may be excessive current in electric circuits are:

1) Direct touching of wires. This may happen if the insulation on the wires has come out due to wear and tear. This may cause a short circuit. A short circuit can result in a very high current flowing through the circuit.
2) Another reason for excessive current can be the connection of many devices to a single socket. This may cause overload in the circuit.
We can prevent excessive current in electric circuits by using a fuse, or MCBs.