What are the components needed in order for an experiment to be valid? Identify these components in the following experiment: A scientist is testing a new plant food to see if it causes plants to grow faster. The scientist tests two plants with the new plant food, and two plants he grows without plant food.

Answers

Answer 1

Answer: He is missing a (real) control. Growing two plants without plant food at all doesn't count; in order to see if the new food is better, he must also grow plants with the original food in order to compare it.

He does have an independent variable. This is the type of plant food. It's independent because he has direct control over it.

He needs to give plants the same conditions besides food: same water (amount), same light exposure, same temperature, etc.

He needs to choose a quantitative way to measure how much the plants grew, like mass or length.

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Five liters of gas at STP have a mass of 12.5 g. What is the molecular mass of the gas? a. 12.5 g/mol b. 25.0 g/mol c. 47.5 g/mol d. 56.0 g/mol e. 125 g/mol
Which of the following is untrue concerning a reversible reaction?a. All reversible reactions will reach equilibrium. b. The reaction always spends equal time in the forward and reverse direction. c. There is equal processing for the concentration of reactants and products. d. The reaction could spend more time in the reverse direction than in the forward direction.
Which of the following is not a valid conversion factor? 1/100 centimeter 1mL/1cm^3 1kilometer/1000 meters 1meter/10 milimeters
What information is necessary to determine the atomic mass of the element chlorine?(1) the atomic mass of each artificially produced isotope of chlorine, only(2) the relative abundance of each naturally occurring isotope of chlorine, only(3) the atomic mass and the relative abundance of each naturally occurring isotope of chlorine(4) the atomic mass and the relative abundance of each naturally occurring and artificially produced isotope of chlorine

2. When lithium reacts with bromine to form the compound LiBr,each lithium atom1) gains one electron and becomes a negatively charged ion2) gains three electrons and becomes a negatively charged ion3) loses one electron and becomes a positively charged ion4) loses three electrons and becomes a positively charged ion

Answers

3) Each lithium atom will lose one electron and become positively charged.

This is an example of ionic bonding wherein an electron is transferred from one atom to another. As each atom wants to have complete outer shells (with lithium's having one electron and bromine's having seven) the electron will move from the Lithium to the Bromine. Lithium will become positive as electrons are negatively charged and it has one less electron than it originally had.

Water can dissolve other substances. Which factor best contributes to this property of water?A. Water is made up of ionic bonds.
B. Water has weak intermolecular forces.
C. Water is denser than most substances.
D. Water particles are not fixed in place.

Answers

Water is known to be theuniversal solvent because it can mostly dissolve most of the substances. Thereason behind its solvability is the bonding of intermolecular forces of attraction.The answer is letter B. Out of the many bondings between molecules, the bondthat governs water is H bonding or hydrogen bonding. Water is composed mostlyof two atoms of hydrogen one atom of oxygen. Both the hydrogen and oxygen arepolar elements and hydrogen is bounded with a high electronegativity oxygen atom.

The correct answer for e2020 is D

In the same science fair,Tina ask the question "does caffeine increase the heart rate of an earthworm?" In test 1,she measures the heart rate by looking at the earthworm under a microscopes, the heart rate if 50 beats per minute. In test 2,she places a few drops of caffeine on the earthworms skin and measures the rate again.in this test the heart rate is 68beats per minuteWhat is the independent variable in this experiment
What is the dependent variable in this experiment
Tina's experiment should have included a hypothisis .in a complete sentence,suggest a hypothesis for Tina's experiment

Answers

The independent variable is the one that does not change depending on other variables - so here it would be the presence or the absence of caffeine - this is dependent on Tina's actions, but not on other variables in the experiment. The dependent variable is the heart rate - it is assumed to depend on the presence or absence of caffeine. A hypothesis could be that "Caffeine causes an increase of heart rate in earthworms" - and this hypothesis is what the experiment is testing.

Based on your findings, which theory about alien thickness seems most valid or most accurate?

Answers

Answer:

C.) Alien thickness is mainly affected by temperature. The greater thickness at lower temperatures may be used as a way to stay warmer in colder weather.

Explanation:

Environmental systems.

Well aliens are like mysteries on Sci-Fi. Aliens aren't humans or just beings that are different from us. When you're saying the thickness, I am assuming about the body of the alien is full of hard and rusty skin that is not like ours.
Hope this helped!!! >.< If not I am sorry....just didn't understand what you were getting to at. I am sorry.

Tobacco's main ingredient is nicotine,alcohol,tar,cigarettes?

Answers

The correct answer is nicotine. It is the main ingredient in a tobacco. Nicotine is an addictive substance thus overuse of the substance will lead to addiction. It acts as a stimulant and a depressant. Tobacco can be dried for smoking and can also be consumed directly.

they are correct, because i had gotten it correct on my test but they are also correct because what they have shown for proof is correct. I had to do research about this in the past, everything they say is 100% correct, and trustworthy.

Hence, the correct answer is nicotine.

Which has should only be produced in a fume hood?a. Cl2
b. CO2
c. H2
d. H2O

Answers

The gas that should only be produced in a fume hood is a. Cl2.
Chlorine gas is toxic gas. Upon inhalation, it irritates the pulmonary tract and damages the respiratory tract. Both short term and long term exposure to Cl2 gas are known to have destructive effects.

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