Which one among the following most correctly determines the atomic number of an element?

• Number of protons

• Number of protons and electrons

• Number of ions

• Number of nucleons

A stable nucleus (light with A < 10) has

• exactly the same number of neutrons and protons

• more neutrons than protons

• no neutrons

• no protons

In oxidation,

1. hydrogen is displaced from a substance.
2. an electropositive element is added to or proportion of electropositive element increases in a substance.

Select the correct answer using the code given below:

• 1 only

• 2 only

• Both 1 and 2

• Neither 1 nor 2

224.

When a copper rod is dipped in an aqueous silver nitrate solution, the color of the solution changes to blue. This is because

• Cu is more easily reduced than Ag

• Ag is more easily reduced than Cu

• Nitrate ion acts as an oxidizing agent

• Nitrate ion acts as a reducing agent

The reaction that takes place in soap making is called saponification. Basically, soap is sodium or potassium salts of

• long-chain monocarboxylic acids

• glycerol

• long-chain dicarboxylic acids

• long-chain tricarboxylic acids

The number of protons in a negatively charged atom (anion) is

• more than the atomic number of the element

• less than the atomic number of the element

• more than the number of electrons in the atom

• less than the number of electrons in the atom

The metal constituent of chlorophyll is

• Iron

• Potassium

• Manganese

• Magnesium

During the explosion of gunpowder, which of the following gases are evolved in the proportion of 1 : 3?

• Oxygen : Nitrogen

• Nitrogen : Oxygen

• Nitrogen : Carbon dioxide

• Carbon dioxide : Nitrogen

Which one among the following is not a mixture?

• Graphite

• Glass

• Brass

• Steel

The metal atom, which is present in superphosphate, is

• sodium (Na)

• potassium (K)

• calcium (Ca)

• magnesium (Mg)