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Subject :NSO    Class : Class 7

Ans 1:

Class : Class 8
i think it should be 4

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Subject :NSO    Class : Class 7

Following are the different steps carried out in a waste water treatment plant. These steps are arranged in a random fashion. Select the option that arranges these steps in the correct sequence.
(i) Wastewater is passed into sedimentation tank.
(ii) Sludge is decomposed by anaerobic bacteria.
(iii) Wastewater is passed through bar screens.
(iv) Wastewater is passed to grit and sand removal tank.
(v) Solids settle at the bottom and floatable materials are removed by skimmer.
(vi) Aeration of water takes place.
(vii) Disinfection of water by adding chlorine.

A(iii) → (i) → (iv) → (v) → (ii) → (vi) → (vii)
B(iii) → (iv) → (i) → (v) → (ii) → (vi) → (vii)
C(iv) → (vi) → (v) → (iii) → (ii) → (i) → (vii)
D(iv) → (v) → (vii) → (ii) → (vi) → (i) → (iii)


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Subject :NSO    Class : Class 7

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Subject :NSO    Class : Class 7

Three solutions of different substances P, Q and R gave the following results with different indicators.
Solution P : Turns methyl orange red.
Solution Q : Turns turmeric solution red.
Solution R : Turns phenolphthalein solution pink.
Identify the solutions P, Q and R respectively

AAntacid, soap solution, lemon juice
BBaking soda, shampoo, antacid
CLemon juice, sodium hydroxide, baking soda
DVinegar solution, antacid, lemon juice.


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Subject :NSO    Class : Class 7

Observe the given experimental setup carefully.

Which of the following statements is/are correct?
1. The nails in flask I will rust because both water and oxygen are available.
2. Nails in flask II will not rust because tap water contains impurities.
3. Nails in flask III will not rust because both oxygen and water are not available.

A2 only
B1 and 3 only
C3 only
DNone of these


Answer should be C as it the nails are covered with calcium chloride which removes water vapour from air so statement 3 should be correct

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Subject :NSO    Class : Class 7

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Subject :NSO    Class : Class 7

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Subject :NSO    Class : Class 6

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Subject :NSO    Class : Class 6

Which of the following statements is false?

AMeasuring tape is not suitable to measure the girth of a tree.
BA suitable measuring device is must to measure the length of an object.
CIn ancient India, small length measurements used were an angul or a mutthi.
DElectric trains, monorail, supersonic aeroplanes and spacecrafts are some of the 20th century contributions.


I could not understand the solution to this question at all. Please give clearer and accurate solutions.

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Subject :NSO    Class : Class 7

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