Iron scraps are advisable and advantageous than zinc scraps for reducing the low grade copper ores. Why?

Zinc liberates hydrogen gas when reacted with dilute nitric acid whereas copper does not. Why ?

Copper is a stronger reducing agent than silver.

a. Write the balanced chemical equations for the extraction of copper metal from its ore. What is the reducing agent used? b. What is the chemical formed as green coating when copper reacts with atmospheric gases in moist conditions?

Rahul visited the house of the friend Shayam and found that all the water laps were rusted. On equiry, he came to know that these were iron taps. Rahul advised his friend to use either chrome plated or nickel plated taps. Shyam accepted his advice. On the basis of above passage give the answer of the following questions: (i) Why did iron tap get rusted? (ii) What was the purpose of chrom plating or nickel plating? (iii) What is the value associated with this?

Explain the following. a] Why is tungsten used almost exclusively for filament of electric lamps? b] Why are the conductors of electric heating devices, such as bread-toasters and electric irons made of an alloy rather than a pure metal? c] Why is the series arrangement not used for domestic circuits? d] How does the resistance of a wire vary with its area of cross-section? e] Why are copper and aluminum wires usually employed for electricity transmission?