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Which one of the following is not a chemical change?
Making a cake
Evaporation of spirit
Exposure of iron to air
Burning of magnesium
A student added a few pieces of zinc into dil.H₂SO₄ taken in a test tube. Suddenly, evolution of gas occurs. What gas is evolved?
Which product is formed when magnesium burns in air?
Why do copper sulphate crystals change colour from blue to white on heating?
Due to dehydration
Due to dehydrogenation
Due to hydration
Due to hydrogenation
Identify X in the following reaction: CuSO₄ (aq)+ H₂S (g)-->X (s) + H₂SO₄ (aq).
What happens when a small piece of iron is kept in copper sulphate solution?
A brown coating appears on the surface of the piece of iron and the colour of the copper sulphate solution turns to light green.
A black coating appears on the surface of the piece of iron and there is no change in the colour of copper sulphate solution.
No characteristic change is observed for both the reactants
A brown coating appears on the surface of the piece of iron and no change happens in the colour of copper sulphate solution.
Which one of the following is a reversible chemical change?
Rusting of iron
Combustion of fuel
Decomposition of ammonium chloride
While performing an experiment, a student adds sodium sulphate solution to a colourless solution. A white precipitate is immediately formed and is insoluble in dil. HCl. The colourless solution is …………………………… & the precipitate formed is……………………
BaCl₂ & BaSO₄
MgCl₂ & NaCl
KCl & NaCl
CH₃COOH & CH₃COONa
When NaOH is added to zinc sulphate solution, a precipitate is formed which is soluble in excess of NaOH. The precipitate obtained is……………………. & the colour of the precipitate is……………….
Zn(OH)₂ & white gelatinous
NaSO₄ & orange- red
NaSO₄ & curdy white
ZnO & red-brown
Identify the product(s) obtained by the reaction of ZnSO
(aq) and H
ZnO (s) & H₂SO₄ (aq)
ZnS (aq) & H₂ (g)
ZnS (s) & H₂SO₄ (aq)
Zn(OH)₂ (aq) & SO₃ (g)
2H₂ + O₂ → 2H₂O is an example of which type of reaction?
On heating Pb(NO₃)₂, what is observed during the reaction?
A crackling sound is produced.
Yellow PbO is obtained.
Brown NO₂ gas is obtained.
All three are observed. (a), (b) and (c).
In the reaction Ba(NO₃)₂ + Na₂SO₄ → X + 2NaNO₃, X is:
Which of the following is an example of combustion?
Take dilute sulphuric acid in a test tube and put a few zinc granules into the test tube. What will you observe?
Zinc granules change to powder.
Colour of zinc changes from grey to white.
The size of zinc granules keep decreasing.
The surface of zinc metal becomes bright.
When magnesium combines with oxygen, it produces magnesium oxide that appears to be like:
When will we observe a precipitate to occur in the solution?
Barium chloride is added to sodium sulphate.
Barium chloride is added to sodium chloride.
Sodium sulphate is added to sodium chloride.
Hydrochloric acid is added to barium chloride.
Barium sulphate is:
Soluble in water.
Partially soluble in water.
Insoluble in water.
A gas at room temperature.
What is observed when burning a magnesium ribbon in air?
A greenish gas is obtained.
It burns brightly, giving out a golden colour.
It burns brightly, leaving blue ash.
It burns brightly, leaving behind white powder.
100 ml of a saturated copper sulphate solution was taken in a beaker. A small amount of iron filings was added to the beaker and left undisturbed overnight. The mixture was then filtered to obtain the residue. The residue was found to be what colour?
When you place an iron nail in copper sulphate solution, the reddish brown coating formed on the nail is _______.
soft and dull
hard and flaky
smooth and shining
rough and granular
What is observed when dilute sulphuric acid is added to zinc granules?
A precipitate is formed.
The reaction mixture turns yellow.
The container becomes hot.
Bubbles start coming from the surface of the Zinc granules.
What happens when blue litmus is added to a water extract of MgO?
It turns red.
It becomes colourless.
It turns green.
No change is observed.
Which of the following is a double displacement reaction?
2H₂O → 2H₂ + O₂
NaCl + AgNO₃ → NaNO₃ + AgCl
Zn + H₂SO₄ → ZnSO₄ + H₂
CH₄ + 2O₂ → CO₂ + 2H₂O
What is obtained when Cu reacts with silver nitrate?
Why does iron displace copper from its salt solution?
Both Fe and Cu are equally reactive.
Fe is less reactive than Cu.
Fe is more reactive than Cu.
None of the above.
Which diagram shows the safest method to detect hydrogen gas produced in a reaction?
Which one of the following is not observed, when a magnesium ribbon is burnt in the flame of a Bunsen burner?
A white powder is formed
A black powder is formed
Magnesium ribbon burns brightly
The powder collected turns moist red litmus paper to blue colour
Why is magnesium ribbon held with a pair of tongs and not with bare hands, when it is burnt in air?
Magnesium is a good conductor of heat so gets very hot
Magnesium is corrosive and burns the skin
Magnesium is slippery
None of these
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