Very short answer questions
(V.S.A) : X Chemical reactions and
Chemical Equation:FA
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1.
Arrange the following metals in the decreasing under of reactivity or electro
positive character.
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K Zn
Na Fe Pb Cu
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2.
Which of them will be a reducing agent a metal or non metal?
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3.
Balance the chemical equation
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4.
Select the combination reaction from following
(i)KClO3
® KCl + 3 O2
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5.
Select the decomposition reaction from following
(i)
2H2O + O2 ® 2H2 O
(ii)
CaCO3 ------Heat------® CaO + CO2
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6.
Select the double displacement reaction
(i)
BaCl2 + H2SO4 ---® Ba SO4 + H2
(ii)
2KBv + Cl2 ® K Cl2 + Bv2
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7.
Fill in the following about reactivity series of metal
(a)
the …………………. Metal replaces the ………………. Metal from its salt solution.
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8.
Which of the following is not the necessary condition for rusting
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(i)
Presence of oxygen (ii) Presence of catalyst (iii) Presence of moisture
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9.
Which of the following is required for prevention of corrosion?
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(i)
coating of less electropositive metal
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(ii)
coating of move electropositive metal
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10.
Choose the correct about rancidity
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(i)
Rancidity is a reduction process (ii) Rancidity is an oxidation
process
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Answers
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1. K
> Na > Zn > Fe > Pb > Cu
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2. Non
metal
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3. 2
Na(s) +2 H2O ® 2NaOH
+ 2H2
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4. S +
O2 ® SO2
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5.
CaCO3 ------Heat® CaO + CO2
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6.
BaCl2 + H2SO4 ® Ba SO4 + H2
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7.
Strong, Weak
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8.
Presence of catalyst
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9.
Coating with move electropositive metal
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10.
Rancidity is an oxidation process
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See some
questions: Short Answer type Question (2 marks)
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1.
(i) What happens when aqueous solution of barium chloride is added to aqueous
sodium sulphate solution?
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(ii)
When silver coloured metal (A) is added to dilute sulphuric acid, solution
(B) is formed which is colourless solution and a gas (c) is evolved which is
colourless name ‘A’, ‘B’ and ‘C’ and write the equation?
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(iii)
An ‘A’ blue coloured crystalline salt on heating decomposes to ‘B’ white
substance. W hen in
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blue
salt solution, a metal (Zinc) is added, its gives rise to colourless solution
‘C’ wth leaving behind ‘D’ reddish brown metal.
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2.
Name the compounds ‘A’, ‘B’, ‘C’ and ‘D’
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(iv)
A reaction mixture of chromium Oxide is heated with aluminum powder on
strong heating
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3.
a. Write the reaction?
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b.
Give one application of this reaction?
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(v)
Define Rusting?
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4.
Give two methods of protection of metal trans rusting.
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5.
(i) Rusting is a slow electrochemical process in which hydrated oxide of
metal in formed from metal when it comes in with air moisture (ii) By
Painting, by galvanization, by tinning
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6.
(i) Explains the term ‘corrosion’?
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(ii)
Write the chemical reaction of corrosion of Iron?
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(iii)
Name two metals which corrodes easily?
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(iv)
Aluminum corrodes in moist air but is widely used is making utensils.
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(v)
what is galvanization and why do we use Zn for it?\
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7.
(i) What is rancidity? Where does it happen
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(ii)
what are anti oxidants? Why are they added fat and oil containing food to
prevent from rancidity?
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(iii)
why do most items puffed with nitrogen.
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Solution:
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1.
White precipitate of BaSO4 is obtained. Reaction will be as
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Na2SO4 +
BACl2 ----------------® BaSO4 + 2NaCl
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2. A
is Zinc, B is ZnSO4 solutions C is H2gas and reactions will be
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Zn (s)
+ H2SO4 (d) ------------® Zn SO4 (aq) + H2 (g)
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3. A,
B, C, and D are respectively-
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CuSO4,
5 H2O, CuSO4, ZnSO4 (aq), Cu (s)
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4.
(i)Cr2O3 + 2Al ------® Al2O3 + 2 Cr
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(ii)
This reaction is used in termite welding
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5. (i)
The process of slow destruction of metals when exposed to air, moisture and
pollutant gases , in called as corrasim
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(ii)
Fe + 3H2 + 2H2O
------------® Fe2O3 x H2O
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(iii)
Formation of green coating on copper and formation of thin layer of oxide on
aluminum are example of corrosion.
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(iv)
Aluminum forms oxide layer on exposure to air, this oxide layer further
checks corrosion.
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(v)
Galvanization is a process in which Zinc layer is applied on Iron. It is used
to protect iron from rusting.
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6. (i)
The oxidative deterioration of oils and fats leading to stinking smell or
stale taste is known as rancidity.
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(ii)
Anti Oxidants are those chemicals which an addition to fat and oil checks it
from rancidityan addition of anti oxidants fatty food is protected from stale.
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(iii)
Nitrogen is filled in potato chips & other food to create anaerobic (air
free atmosphere) which avoids rancidity.
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NCERT Activity Chapter 02 Acid Bases and Salt Class 10 Chemistry Activity 2.1 Indicator Acid Base Red litmus No Change Blue Blue Litmus Red No change Phenolphthalein Colourless Pink Methyl Orange Pink Yellow Indictors are substance which change colour in acidic or basic media. Activity 2.2 There are some substances whose odour changes in in acidic or basic media. These are called olfactory indicators. Like onion vanilla, onion and clove. These changes smell in basic solution. Activity 2.3 Take about 5 mL of dilute sulphuric acid in a test tube and add few pieces of zinc granules to it. => You will observe bubbles of hydrogen gas on the surface of zinc granules. Zn + H2SO4 --> ZnSO4 + H2 => Pass the Hydrogen gas through the soap solution. Bubbles formed in the soap solution as Hydrogen gas it does not get dissolved in it
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