Question

WILL GIVE THE BRAINLEST

Answer questions #1-3 based on the following scenario.
Scientists tested the effect of a fertilizer on the growth of plants. They had 2 sets of plants, Group A which gets fertilizer, water and sun and Group B which gets only water and sun (but in equal amounts to Group A).
1 . Explain how this scenario is a controlled experiment and identify the manipulated variable.



2. If the scientists only performed 1 experiment but it supported their hypothesis, why can it not be considered a theory?



4. You make the following measurements of an object: 42 kg and 22 m3. What would the object’s density be? Show your work for credit and include final units.


5. Explain why a chlorinated swimming pool water would be a homogenous mixture?

6. Both slicing a tomato and a chemical change such as burning toast cannot be reversed. However, why is slicing a tomato still considered only a physical change?

7. If an ice cube melts at 0oC but water also freezes at 0oC, what is the difference between melting and freezing in terms of (a) the energy involved in the phase changes and (b) particles of the substances during the phase changes?


10. If measurements of a gas are 75L and 300 kilopascals and then the gas is measured a second time and found to be 50L, describe what had to happen to the pressure (if temperature remained constant). Include which law supports this observation.





11. Which statement matches the scientists to their research on atomic theory?
a. Dalton used gold foil; Bohr made the planetary model of atoms
b. Thomson used gold foil; Dalton believed atoms had no internal structure
c. Rutherford used gold foil; Thomson discovered electrons
d. Rutherford discovered electrons; Thomson made the planetary model of atoms



For questions #14 – 17, write an equation for the reaction of magnesium chloride and sodium oxide to produce magnesium oxide with sodium chloride.
14. Show the formulas of the reactants.

15. Show the formulas of the products.

16. Write the balanced the equation for this reaction.

17. What type of chemical reaction is this? How do you know?

18. When is an atom unlikely to react and form chemical bonds?

19. What is the order of the types of nuclear radiation from lowest to highest energy?

20. Which statement is false? Rewrite it so that it is true.
a. Fusion involves the combination of two smaller atoms into a larger atom.
b. Fission involves the splitting of an atom into smaller atoms.
c. Fission and fusion are two processes that release very little amounts of energy.
21. What naturally occurring radioisotope is used as the fuel for a nuclear reactor?

22. Magnesium oxide is a binary ionic compound. From its formula, MgO, how do you know that Mg is the metal?

23. On the periodic table, there are two numbers in the block for the element potassium, K: 19 and 39.098. What are the names of the numbers and what do they measure?
24. Element X has five valence electrons, element Y has one valence electron, and element Z has one valence electron. Which two of these elements are most likely to have similar properties? Explain your answer.


Fill in the Blank: Type your answer in the blank, or in the space below the question. Please use ONLY the textbook to create your solutions. Do not use the internet.
25. From left to right across a period in the periodic table, elements become less ___________ and more ______________ in their properties.
26. Francium has 36 isotopes, but only francium-223 occurs in nature. Francium-223 spontaneously emits particles and energy, so francium-223 is a(an) _____________ of francium.
27. At sea level, water ______________ at 100°C.
28. Cooking requires continuous addition of energy to the chemical reactions that are taking place. The chemical reactions involved in cooking can be described as __________________.
29. The ________________ theory of matter states that all particles of matter are in constant motion.
30. In Rutherford’s experiments, some of the _______________ aimed at gold atoms bounced back, suggesting that a solid mass was at the center of the atom.
31. You are given the melting points of three unknown substances and are asked to predict which one is an ionic compound. You would select the compound with the ________________ melting point.
32. A flight simulator that helps astronauts prepare for a shuttle launch is an example of a(an) __________________.
33. In the symbol ■(4@2) He, the superscript 4 is the _________________ for helium, and the subscript 2 is the ___________________ for helium.

Answer 1

Question no. 1:

Answer:

Controlled experiment is an experiment which is designed to test a variable, which can be changed during the experiment.

Explanation:

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.

Question 2:

Answer:

Because theory is the most organised statement proved by a set of independent experiments.

Explanation:

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.

Question no 4.

Answer:

Density = 1.909 kg/m3

Explanation:

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

Hence the density of the object is 1.909 and its unit is kg/m3 which is system international unit of density.

Question 5.

Answer:

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.

Explanation:

• 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.

Question no. 6.

Answer:

Because physical change does not include composition change, it includes change in physical parameters. And in splicing tomato only change in shape is done.

Explanation:

• 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.

Answer 2

Answer:

Controlled experiment is an experiment which is designed to test a variable, which can be changed during the experiment.

Explanation: