Three solutions P, Q and R have pH value of 3.5, 5.2 and 12.2 respectively. Which one of these is a:

1. Weak acid?
2. Strong alkali?

Mention two reasons to explain as to why we are facing water scarcity in recent times.

Two waves of the same pitch have amplitudes in the ratio 1:3. What will be the ratio of their:

(i) intensities and

(ii) frequencies?

What is soil erosion?

Action of alcoholic KOH on bromoethane.

Addition of ethyl alcohol to acetic acid in the presence of concentrated Sulphuric acid.

(i) Define nuclear fission.

(ii) Rewrite and complete the following nuclear reaction by filling in the atomic number of Ba and mass number of Kr:

Write the equation for the reaction that occurs at the cathode during the extraction of aluminum by electrolysis.

Heating of Ethanol at 170oC in the presence of conc. Sulphuric acid.

Write a balanced chemical equation.

NH₄OH Solution when added to the Solution (B) gives white ppt which does not dissolve in excess.

Identify the cations in each of the following case:

The diagram below shows a pulley arrangement:

1. Copy the diagram and mark the direction of tension on each strand of the string.
2. What is the velocity ratio of the arrangement?
3. If the tension acting on the
...

The metal whose oxide, which is amphoteric, is reduced to metal by carbon reduction ____ . (Fe / Mg / Pb / Al)

1. How is the e.m.f. across primary and secondary coils of a transformer related with the number of turns of coil in them?
2. On which type of current do transformers work?

Differentiate between the following pairs on the basis of what is mentioned within brackets:

1. Human skin cell and Human ovum (number of chromosomes)
2. Sperm duct and fallopian tube (function)
3. Red Cross and WHO
...

The process by which sulphide ore is concentrated.

The specific heat capacity of a substance A is 3,800 J kg^-1 K^-1 and that of a substance B is 400 J kg^-1 K^-1. Which of the two substances is a good conductor of heat? Give a reason for your answer.