A change in the physical state can be brought about
(a) only when energy is given to the system
(b) only when energy is taken out from the system
(c) when energy is either given to, or taken out from the system
(d) without any energy change
Which of the following statements is not true about an atom?
(a) Atoms are not able to exist independently
(b) Atoms are the basic units from which molecules and ions are formed
(c) Atoms are always neutral in nature
(d) Atoms aggregate in large numbers to form the matter that we can see,
feel or touch
Calculate the mass of sodium sulphate required to prepare its 20% (mass
percent) solution in 100g of water?
Arun has prepared 0.01% (by mass) solution of sodium chloride in water.
Which of the following correctly represents the composition of the solutions?
(a) 1.00 g of NaCl + 100g of water
(b) 0.11g of NaCl + 100g of water
(c) 0.0l g of NaCl + 99.99g of water
(d) 0.10 g of NaCl + 99.90g of water
You are provided with a mixture containing sand, iron filings, ammonium
chloride and sodium chloride. Describe the procedures you would use to
separate these constituents from the mixture?
During an experiment the students were asked to prepare a 10% (Mass/Mass)
solution of sugar in water. Ramesh dissolved 10g of sugar in 100g of water
while Sarika prepared it by dissolving 10g of sugar in water to make 100g
of the solution.
(a) Are the two solutions of the same concentration
(b) Compare the mass % of the two solutions.
Classify each of the following, as a physical or a chemical change. Give
reasons.
(a) Drying of a shirt in the sun.
(b) Rising of hot air over a radiator.
(c) Burning of kerosene in a lantern.
(d) Change in the colour of black tea on adding lemon juice to it.
(e) Churning of milk cream to get butter.
Iron filings and sulphur were mixed together and divided into two parts,
‘A’ and ‘B’. Part ‘A’ was heated strongly while Part ‘B’ was not heated. Dilute
hydrochloric acid was added to both the Parts and evolution of gas was
seen in both the cases. How will you identify the gases evolved?
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