C) During chemical reaction, total mass remains the same.
This is because due to the law of conservation of mass, stating that in a chemical reaction, neither mass will be created nor destroyed. So, the total mass will not change when chemical reactions occur.
The resistance of two things in series is the SUM of their individual resistances. So the resistance of two bulbs in series is <u><em>double</em></u> the resistance of one bulb.
(If they're in parallel, their combined resistance is <u><em>1/2</em></u> the resistance of one bulb.)
So two bulbs <em>in series</em> is the greater resistance. <em>(a) </em>
Left. Use right hand rule. Have hand wide open. Thumb points in direction of current.(which makes right angle with your index finger) Four fingers in direction of magnetic field and your palm should point in the direction of the force