Sucrose (sugar) crystals obtained from sugarcane and beetroot are mixed
together. Will it be a pure substance or a mixture? Give reasons for the
same.
Fill in the blanks
(a) A colloid is a ——— mixture and its components can be separated by
the technique known as ———.
(b) Ice, water and water vapour look different and display different ——
properties but they are ——— the same.
(c) A mixture of chloroform and water taken in a separating funnel is mixed
and left undisturbed for some time. The upper layer in the separating
funnel will be of——— and the lower layer will be that of ———.
(d) A mixture of two or more miscible liquids, for which the difference in
the boiling points is less than 25 K can be separated by the process
called———.
(e) When light is passed through water containing a few drops of milk, it
shows a bluish tinge. This is due to the ——— of light by milk and the
phenomenon is called ——— . This indicates that milk is a ———
solution.
Give an example each for the mixture having the following characteristics.
Suggest a suitable method to separate the components of these mixtures
(a) A volatile and a non-volatile component.
(b) Two volatile components with appreciable difference in boiling points.
(c) Two immiscible liquids.
(d) One of the components changes directly from solid to gaseous state.
(e) Two or more coloured constituents soluble in some solvent.
An element is sonorous and highly ductile. Under which category would
you classify this element? What other characteristics do you expect the
element to possess?
What are the favourable qualities given to gold when it is alloyed with copper
or silver for the purpose of making ornaments?
You are given two samples of water labelled as ‘A’ and ‘B’. Sample ‘A’ boils at 100°C and sample ‘B’ boils at 102°C. Which sample of water will not
freeze at 0°C? Comment.
Name the process associated with the following
(a) Dry ice is kept at room temperature and at one atmospheric pressure.
(b) A drop of ink placed on the surface of water contained in a glass spreads
throughout the water.
(c) A potassium permanganate crystal is in a beaker and water is poured
into the beaker with stirring.
(d) A acetone bottle is left open and the bottle becomes empty.
(e) Milk is churned to separate cream from it.
(f) Settling of sand when a mixture of sand and water is left undisturbed
for some time.
(g) Fine beam of light entering through a small hole in a dark room,
illuminates the particles in its paths.
The teacher instructed three students ‘A’, ‘B’ and ‘C’ respectively to prepare
a 50% (mass by volume) solution of sodium hydroxide (NaOH). ‘A’ dissolved
50g of NaOH in 100 mL of water, ‘B’ dissolved 50g of NaOH in 100g of
water while ‘C’ dissolved 50g of NaOH in water to make 100 mL of solution.
Which one of them has made the desired solution and why?
Classify the following as physical or chemical properties
(a) The composition of a sample of steel is: 98% iron, 1.5% carbon and
0.5% other elements.
(b) Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas.
(c) Metallic sodium is soft enough to be cut with a knife.
(d) Most metal oxides form alkalis on interacting with water
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