WHAT WILL HAPPEN TO THE RESISTANCE OF CONDUCTOR IF : 1. the length of the wire is halved?
2. the area of cross-section of the conductor is increased?
3. the temperature of the conductor is increased?

1. The length of the wire is halved.

the resistance of a conductor is directly proportional to it's length (L) as R - L. Thus doubling it's length will double it's resistance, while halving it's length would halve the resistance. Also the resistance of a conductor is inversely proportional to it's cross sectional area.

2. The area of cross-section of the conductor in increased.

On increasing the area of cross-section, resistance decreases. Thus is because resistance is inversely proportional to area.

3. The temperature of the conductor is increased.

With increasing temperature, the resistance of the wire increases as collisions within the wire increases and "slow" the flow of current... Since conductors typically display an increased resistivity with temperature increase, they have a positive temperature coefficient.

if you mean hydrogen and oxygen then water is the product

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.