Science - NCERT Solutions - GeniusJnr

Science - NCERT Solutions : MCQ, free quiz, mock quiz, practise questions, olympiad preparation

Science - NCERT Solutions

Chapters

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Matter in Our Surroundings

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Is Matter Around Us Pure

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Atoms and Molecules

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Structure of the Atom

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The Fundamental Unit of Life

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Tissues

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Videos

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video lecture

Characterstics of Matter

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Evaporation and Factors Affecting Evaporation

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Quiz

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Practice Test 1

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mcq

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Practice Test 3

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Practice Test 4

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Matter in Our Surroundings: Written Test

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States of Matter - Class Test

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Evaporation - Class Test

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Questions

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A gaseous mixture contains oxygen and nitrogen in the ratio of 1:4 by mass. Therefore, the ratio of their number of molecules is;

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Cellulose upon acetylation with excess acetic anhydride/ H₂SO₄(catalytic) gives cellulose triacetate whose structure is

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STATEMENT 1: There is a natural asymmetry between converting work to heat and converting heat o work.
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STATEMENT 2: No process is possible in which the sol result is the absorption of heat from a reservoir and its complete conversion into work.

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An incomplete distribution is given as follows:

Variable:	0−10	10−20	20−30	30−40	40−50	50 − 60	60 − 70
Frequency:	10	20	?	40	?	25	15

You are given that the median value is 35 and the sum of all the frequencies is 170. Using the median formula, fill up the missing frequencies.

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Calculate the median from the following data:

Marks below:	10	20	30	40	50	60	70	80
No. of students:	15	35	60	84	96	127	198	250

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Following is the distribution of I.Q. of 100 students. Find the median I.Q.

I.Q.:	55−64	65−74	75−84	85−94	95−104	105−114	115−124	125−134	135-144
No. of students:	1	2	9	22	33	22	8	2	1

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Use the following information to answer the next two questions.

Martha mixed some marble powder with dry ice. On keeping the mixture in open air for a few minutes, the dry ice vanished and only the dry powder was left behind.

The dry ice vanished because of

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Following are the lives in hours of 15 pieces of the components of aircraft engine. Find the median:

715, 724, 725, 710, 729, 745, 694, 699, 696, 712, 734, 728, 716, 705, 719

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Crystalline solids have

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To find out the concentration of SO₂ in the air (in parts per million, i.e., ppm), the data was collected for 30 localities in a certain city and is presented below:

Concentration of SO₂ (in ppm)	Frequency
0.00−0.04 0.04−0.08 0.08−0.12 0.12−0.16 0.16−0.20 0.20−0.24	4 9 9 2 4 2

Find the mean of concentration of SO₂ in the air.

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In a retail market, fruit vendors were selling mangoes kept in packing boxes. These boxes contained varying number of mangoes. The following was the distribution of mangoes according to the number of boxes.

Number of mangoes:	50−52	53−55	56−58	59−61	62−64
Number of boxes:	15	110	135	115	25

Find the mean number of mangoes kept in a packing box. Which method of finding the mean did you choose?

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Use the following information to answer the next question.

The rate of evaporation with an increase in temperature and with an increase in humidity.

The information in which alternative completes the given statement?

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