Name the substance oxidized and reduced in the given reaction:

Name the pigment which transports oxygen and carbon dioxide in the human body.

Write the SI unit of resistivity.

A silver spoon is kept immersed in an aqueous solution of copper sulfate. What change would be observed in the spoon as well as in the solution? Justify your answer.

Why do we store silver chloride in dark coloured bottles?

Name the correct substrates for the following enzymes:

a. Trypsin

b. Amylase

c. Pepsin

d. Lipase

Three 2Ω resistors, A,B and C, are connected as shown in the figure. Each of them dissipates energy and can withstand a maximum power of 18 W without melting. Find the maximum current that can flow through the three resistors.

How does use of a fuse wire protect electrical appliances?

Write the balanced chemical equations for the following reactions.

a. Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogen carbonate.

b. Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodium chloride, water and liberates carbon dioxide.

c. Copper sulphate on treatment with potassium iodide precipitates cuprous iodide (Cu₂I₂), liberates iodine gas and also forms potassium sulphate.

How does aerobic respiration differ from anaerobic respiration?

State reason for the following:

a. In human heart, the walls of the ventricles are thicker than the auricles.

b. During the breathing cycle, even after forceful exhalation, the exchange of gases continues.

c. In green plants during the day carbon dioxide is generated in respiration but is not released out.

Three resistors are connected as shown in the figure. Through the resistor 5 ohms, a constant current of 1 ampere is flowing.

a. What is the current through the other two resistors?

b. What is the potential difference across AB and across AC?

c. What is the total resistance?

On heating blue coloured powder of copper (II) nitrate in a boiling tube, copper oxide (black), oxygen gas and a brown gas X is formed.

a. Write a balance chemical equation of the reaction.

b. Identify the brown gas X revolved.

c. Identify the type of reaction.

d. What could be the pH range of aqueous solution of the gas X?

Describe the process of urine formation in kidneys.

a. Give reasons for the following:

i. Tungsten used almost exclusively for filament of electric lamp.

ii. Copper and aluminium wires are usually employed for electricity transmission.

b. Describe an activity with the help of circuit diagram to show that potential difference across each resistor connected in parallel is same.