Chemical Bonding — Chemistry STD 10 — Question

The primary reason behind the formation of the toxic foam is high phosphate content in the wastewater because of detergents used in dyeing industries, dhobi ghats and households. Yamuna's pollution level is so bad that parts of it have been labelled 'dead' as there is no oxygen in it for aquatic life to survive.
(i) Predict the pH value of the water of river Yamuna if the reason for froth is high content of detergents dissolved in it.
(ii) The pH value of four solutions P, Q, R and S are 2, 9, 5 and 11 respectively. Arrange the solutions in in- creasing order of their hydronium ion concentration. Identify strong acid.
(iii) When the water has detergents dissolved in it. What is the level of concentration of hydronium ion and hydroxide ion?
(iv) If a sample of water containing detergents is provided to you, which method will you adopt to neutralise it?

How is ore purified (give equations also)

The electro negativities (according to Pauling) of the elements in period 3 of the periodic table are as follows.
The elements are arranged in alphabetical order:
Al Cl Mg Na P S Si
1.5 3.0 1.2 0.9 2.1 2.5 1.8
(i) Arrange the elements in the order in which they occur in the periodic table from left to right.
(The group 1 elements first, followed by the group 2 element and so on, up to group 7)
(ii) Choose the word or phrase from the brackets which correctly completes each of the following statements:
(a) The element below sodium in the same group would be expected to have a ______ (lower/higher) electro negativity than sodium and the element above chlorine which would be expected to have a ______ (lower / higher) ionization potential than chlorine.
(b) On moving from left to right in a given period, the number of shells ______ (remains the same / decreases/ increases).
(c) On moving down a group, the number of valence electrons ______ (remains the same / increases/ decreases).

List the properties of ammonia that make it
(i) A good refrigerant
(ii) A cleaning agent
(iii) As a source of hydrogen

Hydrogen chloride gas is very soluble in water. It is dissolved in water to prepare hydrochloric acid by using an anti-suction device, as shown in the diagram. Very briefly explain how this device prevents the suction of water into the flask, in which hydrogen chloride gas is produced.

A metal article is to be electroplated with silver. The electrolyte selected is sodium argentocyanide.
(a) What kind of salt is sodium argento cyanide?
(b) Why is it preferred to silver nitrate as an electrolyte?
(c) State one condition to ensure that the deposit is smooth, firm and long lasting.
(d) Write the reaction taking place at the cathode.
(e) Write the reaction taking place at the anode.

Four elements A, B, C, D and E have the following electron arrangements in their atoms:

A	2, 8, 6
B	2, 8, 8
C	2, 8, 8, 1
D	2,7
E	2, 8, 2

(i) What type of bond is formed when 'A' combines with 'C'?
(ii) Which two elements will combine to form a covalent bond?
(iii) Which element is not able to form any type of bond?
(iv) Draw electron dot structure of bond formation of 'A' molecule.
(v) Which ion will be formed by 'D' to attain stability? Justify with the chemical equation.

Draw the structures of isomer of : pentane. Write the IUPAC and common names of these isomer

Copy and complete the following table.
Column 3 has the names of gases to be prepared using the substance you enter in column 1, along with dilute or concentrated sulphuric acid, as indicated in column 2.

Column 1	Column 2	Column 3
Substance reacted with acid	Dilute or concentrated sulphuric acid	Gas
		Hydrogen
		Carbon dioxide
		Only chlorine

Write the equation for the laboratory preparation of :
(i) Sodium sulphate using dilute sulphuric acid.
(ii) Lead sulphate using dilute sulphuric acid.