Explore topic-wise InterviewSolutions in .

Periods are ___ (rows/columns) in the modern periodic table.

Fill in the following blanks with suitable words :

(a) Acids have a pH ___ than 7.

(b) Alkalis have a pH ___ than 7.

(c) Neutral substances have a pH of __

(d) The more acidic a solution, the ___ the pH.

(e) The more alkaline a solution, the ___ the pH.

How does water get polluted?

Give reason: Generally for making gold ornaments, 22-carat gold is preferred over 24-carat gold. [2 MARKS]

In a bakery, baking powder was not added while preparing cake the cake obtained was hard and small in size. what is the reason for this?

One of the following is an exothermic reaction. This is :

(a) electrolysis of water

(b) conversion of limestone into quicklime

(c) process of respiration

(d) process of photosynthesis

(a) Give the chemical names and formulae of main ores of (i) aluminium (ii) iron (iii) zinc.

(b) Which impurities are present in bauxite.

(c) What is red mud, how is it removed?

What is efflorescence ? Name one compound which exhibits efflorescence . Support your answer by giving balanced equation .

Which of the following gas is liberated when red lead is heated with concentrated hydrochloric acid?

(a) Explain the term "corrosion" with an example. Write a chemical equation to show the process of corrosion of iron.

(b) What special name is given to the corrosion of iron ?

(c) What type of chemical reaction is involved in the corrosion of iron ?

(d) Name any three objects (or structures) Which are gradually damaged by teh corrosion of iron and steel.

A metal X forms a salt $XS{O}_4$. The salt $XS{O}_4$ forms a clear solution in water which reacts with sodium hydroxide solution to form a blue precipitate Y. Metal X is used in making electric wires and alloys like brass.

(a) What do you think metal X could be ?

(b) Write the name, formula and colour of salt $XS{O}_4$

(c) What is the blue precipitate Y ?

(d) Write a chemical equation of the reaction which takes place when salt $XS{O}_4$ reacts with sodium hydroxide solution. Give the state symbols of all the reactants and products which occur in the above equation.

Question 43
On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, a white precipitate is obtained.

(a) Write a balanced chemical equation of the reaction involved.

(b) What other name can be given to this precipitation reaction?

(c) On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?

Element present in middle lamella

The following two molecules are examples of
$C{H}_3-C{H}_2-O-C{H}_2-C{H}_{3}C{H}_3-C{H}_2-C{H}_2-C{H}_2-OH$

Parts (a) to (e) refer to changes in the properties of elements on moving from left to right across a period of Periodic Table. For each property, choose the correct answer.

(a) The non-metallic character of the elements :

(i) decreases, (ii) increases,

(iii) remains the same, (iv) depends on the period

(b) The electronegativity :

(i) depends on the number of valence electrons,

(ii) remains the same,

(iii) decreases,

(iv) increases.

(c) The ionization potential :

(i) goes up and down (ii) decreases

(iii) increases (iv) remains the same

(d) The atomic size :

(i) decreases,

(ii) increases,

(iii) remains the same ,

(iv) sometimes increases and sometimes decreases.

(e) The electron affinity of the elements in groups 1 to 7 :

(i) goes up and then down.

(ii) decreases and then increases,

(iii) increases,

(iv) decreases.

(a) State two properties of brass that render it more useful for some purposes than its components.

(b) a metal which forms a liquid alloy at ordinary temperature.

Calculate:

(a) the gram molecular mass of chlorine if $308c{m}^3$ of it at STP weiths, 0.979 g,
(b) the volume of 4 g of$H_2$ at 4 atmosphere,
(c) the mass fo oxygen in 2.2 litres of $C{O}_2$ at STP.

When an iron nail is placed in copper sulphate solution, we observe colour changes whereas when copper wire is placed in iron sulphate solution, we observe no change in colour. What is the reason behind this change in the test tube?

List some differences between minerals and ores.

Write the chemical reaction when iron reacts with dilute $H_{2}S{O}_4$ ?

Distinguish between metals and non-metals on the basis of:

(i) ion information, (ii) discharge of ions, (iii) nature of oxide formed, (iv) oxidising and reducing property, (v) reaction with acids.

What is the difference between the food habits of organisms belonging to the first and the third trophic levels? Give one example each of the organisms belonging to these two trophic levels.

a) What is universal indicator .

b) What is the chemical equation involved in the preparation of sodium hydroxide. Name the process.

c) Give reason for; Dry hydrogen chloride gas does not turn blue litmus red whereas dilute hydrochloric.

Why are alkali metals highly reactive in air?

What will happen if silver bromide is kept for some time in sunlight?

Why is it important to balance a chemical equation?

1. 60

What happens when sodium ethanoate is heated with soda lime?

pH of black coffee?

(a) What is bleaching powder? How is bleaching powder prepared? Write the chemical equation of the reaction involved in the preparation of bleaching powder.

(b) What happens when bleaching powder reacts with the dilute sulphuric acid? Give the equation of the reaction involved.

(c) State two important uses of bleaching powder.

What are the two main ways in which common salt (sodium chloride) occurs in nature ?

Metals react with nitric acid to form __________.

(a) Name the first three alkaline earth metals.

(b) Write their reactions with dil hydrochloric acid.

Identify the salt which cannot react with NH₄OH solution.

when concentrated acid is added to water identify whether the process is exothermic or endothermic ??

Why magnesium and calcium don't react with cold water?

Identify from the following which is not an oxidising agent.

What are the different types of ecosystems?