1994 年

If the atomic number of an element X is 13, the formula of its oxide is

Consider the information given in the table below:

Which of the following atoms are isotopes ?

Which of the following molecules has the greatest number of lone pairs of electrons ?

Both rubidium (Rb) and sodium are elements in Group I of the Periodic Table, but rubidium is more reactive than sodium. When a rubidium hydroxide solution is electrolyzed using platinum electrodes, hydrogen gas is liberated at the cathode. Which of the following statements is a correct explanation for the phenomenon described above ?

Directions: Q.6 and Q.7 refer to the following experiment: A drop of silver nitrate solution and a drop of sodium iodine solution are placed respectively at X and Y as shown in the diagram below:

After the circuit has been closed for some time, a coloured patch is formed between X and Y. What is the colour of the patch ?

Directions: Q.6 and Q.7 refer to the following experiment: A drop of silver nitrate solution and a drop of sodium iodine solution are placed respectively at X and Y as shown in the diagram below:

The main aim of this experiment is to show that

Which of the following contains the same number of atoms as 2.20 g of carbon dioxide ? (Relative atomic masses: H = 1.0, C = 12.0, N = 14.0, O = 16.0, S = 32.0, Cl = 35.5)

On strong heating, a solid X decomposes to give a solid residue and a brown gas. The solid residue can react with concentrated nitric acid with evolution of a brown gas. X is probably

In which of the following experiments will a redox reaction occur ?

When a substance X is electrolyzed using platinum electrodes, a gas is collected at each electrode. X may be