<h2>Question no. 1:
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Controlled experiment is an experiment which is designed to test a variable, which can be changed during the experiment.
<h3>Explanation:
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Hence in this experiment, the importance of experiment is being tested, as it is added only in one set of plant.
A manipulated variable is an independent variable whose amount can be changed during an experiment.
Here the fertilizer is a manipulated variable.
<h2>Question 2:
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Because theory is the most organised statement proved by a set of independent experiments.
<h3>Explanation:
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Hypothesis is the initial idea on which basis different experiments are conducted. But if 1 experiment succeeded and it supports the hypothesis, hypothesis do not become a theory.
For a theory, different experiments are necessary which supports that hypothesis.
<h2>Question no 4.
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Density = 1.909 kg/m3
<h2>Explanation:
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Given data:
Mass of the object = 42 kg
Volume of the object = 22 m3
Density of the object = ?
Solution
Density = mass/volume
Density =42/22 = 1.909
Density = 1.909 kg/m3
<u><em>Hence the density of the object is 1.909 and its unit is kg/m3 which is system international unit of density.
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<h2>Question 5.
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Chlorine and water in swimming pool are mixed in such a way that there composition remains same throughout the mixture. And chlorine cannot be separated back from water. This is the homogeneous mixture.
<h3>Explanation:
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- A homogeneous mixture is a mixture of more than one substance which are mixed together in such a way that they cannot be separated and the composition of the mixture remains same throughout the mixture.
- Example of homogeneous solution is sugar solution in water.
- As for swimming pool cleaning chlorine is added in pool water, it mixes in the whole water by diffusion. Hence it is a homogeneous mixture.
<h2>Question no. 6.
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Because physical change does not include composition change, it includes change in physical parameters. And in splicing tomato only change in shape is done.
<h3>Explanation:
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- Chemical change means irreversible chemical composition change like the burning of toast.
- Physical change means reversible or irreversible change in shape, volume density without change in chemical composition.
- Splicing tomato comes under 2nd category because it does not include chemical change.
Remaining questions are attached in the files.
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