Is Matter Around Us Pure ? Science - Is Matter Around Us Pure ?

Pure iodine can be obtained by the process of ______________?

Which of the following will scatter light:

The number of phases present in a true solution is:

The property/ properties which enable copper metal to be used for making electric wires is/ are:

In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R).
Mark the correct choice as:

1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
2. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
3. If Assertion is true but Reason is false.
4. If Assertion is false and Reason is true.
5. If both Assertion and Reason are false.

Assertion: A mixture of acetone and methanol can be separated by fractional distillation.
Reason: The difference between boiling point of acetone and methanol is very less.

In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R).
Mark the correct choice as:

1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
2. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
3. If Assertion is true but Reason is false.
4. If Assertion is false and Reason is true.
5. If both Assertion and Reason are false.

Assertion: Tyndall effect is an optical property.
Reason: Scattering of beam of light by the colloidal particles is known as Tyndall effect.

In the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:

1. Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
2. The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
3. Assertion is true but the Reason is false.
4. The statement of the Assertion is false but the Reason is true.

Assertion: Dust particle in air form aerosol.
Reason: Dust particles form dispersion medium and air is dispersed phase.

In the following questions, a statement of Assertion (A) is followed by a statement of Reason (R).
Mark the correct choice as:

1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
2. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
3. If Assertion is true but Reason is false.
4. If Assertion is false and Reason is true.
5. If both Assertion and Reason are false.

Assertion: Colloidal particles do not show Tyndall effect.
Reason: Colloidal solutions are stable and the colloidal particles do not settle down.

State whether the following statement is true or false:
Milk is a pure substance.

Sea water is a mixture.

State whether the following statements are true or false:
Alcohol can be separated from a mixture of alcohol and water by a separating funnel.

Gases can be liquified at low temperature and low pressure.

Name one pair of liquids which can be separated by using a separating funnel.

Fill in the blanks:
A colloid is a _________ mixture and its components can be separated by the technique known as ________.

Physical changes are generally..........

Fill in the following blanks with suitable words:
The three important metalloids are __________ and __________.

Fill in the blanks:
Ice, water and water vapour look different and display different _________ properties but they are_________ the same.

Mixture of ammonium chloride and sodium chloride can be separated by _______.

Name a non-metal:
Which is known to form the largest number of compounds.

Is ink a pure substance or mixture? Give reason.

Name a liquid which can be classified as a pure substance and conducts electricity.

Name a non-metal which is a good conductor of electricity.

Name the process you would use to separate a mixture of water and alcohol.

Define a compound. Give two points of evidence to show that sodium chloride is a compound.

Name the process associated with the following:
A drop of ink placed on the surface of water contained in a glass spreads throughout the water.

Which of the following are chemical changes and which physical? Give reason.

1. A glass bottle breaking.
2. Coal burning in air.
3. Making a cake.
4. Wool being knitted into a sweater.

Classify the following as physical or chemical changes:

1. Formation of curd from milk.
2. Condensation of steam.
3. Growth of a plant.
4. Breaking of a glass tumbler.

Enumerate any two differences between sample distillation and fractional distillation.

Melting of wax is a physical change but burning of wax is a chemical change. Explain.

What are (i) metals (ii) non-metals, and (iii) metalloids? Give two examples each of metals, non-metals and metalloids.

Non metals are usually poor conductors of heat and electricity. They are non-lustrous, non-sonorous, non-malleable and are coloured.

1. Name a lustrous non-metal.
2. Name a non-metal which exists as a liquid at room temperature.
3. The allotropic form of a non-metal is a good conductor of electricity. Name the allotrope.
4. Name a non-metal which is known to form the largest number of compounds.
5. Name a non-metal other than carbon which shows allotropy.
6. Name a non-metal which is required for combustion.

The solubility of potassium nitrate at 20°C is 32g per 100g of water. How much salt is required to prepare 66g of its saturated solution?

Explain the following giving examples.
Suspension.

How are sol, solution and suspension different from each other?

What is crystallisation? How can this technique be used to purify impure copper sulphate?

Give the main differences between physical changes and chemical changes.

Define the following:

1. Sol
2. Aerosol
3. Emulsion
4. Foam

Given one example of each.

The given mixture contains three constituents A, B and C. The constituent A is a yellow coloured, solid element which dissolves in a liquid D. The constituents B is a blue coloured salt which is insoluble in liquid D but dissolves easily in another liquid E. The constitudent C is a liquid wlich is used in coolking food and forms a solid fat on hydrogenation.

1. What do you think could (i) constituent A, and (ii) liquid D be?
2. What could (i) constituent B, and (ii) liquid E be?
3. What could liquid C be?
4. How will you separate the mixture containing A, B and C.

100ml of water at room temperature of 25°C is taken in a beaker and a little of solid S is dissolved in it by stirring to obtain a solution X. More and more of solid S is added to the solution with constant stirring, while keeping the temperature of solution constant at 30°C. After some time it is observed that no more solid dissolves in water and at the same time some solid is also left undissolved at the bottom of the beaker. The contents of beaker are filtered through a filter paper to obtain solution Y in the form of a filtrate.

1. What name is given to solutions like X?
2. What name is given to solution like Y?
3. What will you observe if the solution Y at 30°C is cooled down to 10°C by keeping the beaker in crushed ice? Why?
4. What term is used to denote the amount of solid dissolved in 100 grams of water in a solution like Y?

When the solid A is added to water, it dissolves with the evolution of a lot of heat and making little explosions to form two products B and C. The properties of products B and C are entirely different from those of solid A as well as water. Moreover, products B and C cannot be reconverted into solid A and water. When another solid D is added to water, it dissolves with the absorption of a little heat to form a product E which cools down. The product E shows the properties of both, solid D as well as water. Moreover, product E can be converted into solid D and water.

1. What type of change occurs when solid A is dissolved in water? Why?
2. What type of change occurs when sold D is dissolved in water? Why?
3. Name a metal which you think could behave like solid A. Also name the products B and C.
4. Name the solid D if it is the one which is used in making ordinary dry cells.
5. Name the process by which D can be recovered from E.

Tincture of iodine is a mixture of two materials X and Y. The material Y has a property that its solid form can be converted directly into vapours on heating by a process called Z.

1. What could X be?
2. What could Y be?
3. Name the process Z.
4. Which process would you use to recover both the components X and Y from tincture of iodine?
5. Which process can be used to recover only component Y from tincture of iodine?

The liquid air has three components X, Y and Z whose boiling points are: -186°C, -183°C and -196°C, respectively. When liquid air is fed into a tall fractional distillation column from near its bottom and warmed up slowly:

1. Which component will be collected from near the bottom of the fraction distillation column? Why?
2. Which component will be collected from the top part of the fractional distillation column? Why?
3. Which component will be collected from the middle part of the fractional distillation column? Why?
4. What could the component X, Y and Z be?