A scientist discovers that an atom with a mass number of 14 contains eight electrons.

Q4. What are the different ways in which human being use rocks ?

Ghella [55]

Answer:

To hit someone on the head

Explanation:

self protection

4 0

3 years ago

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An aqueous solution of potassium sulfate is allowed to react with an aqueous solution of calcium nitrate. identify the solid in

Maksim231197 [3]

Ans: Calcium sulfate.

K2SO4 (aq) + Ca(NO3)2 (aq) ⇒ 2KNO3 (aq) + CaSO4 (s)

6 0

3 years ago

2. Problem: Is colored or black and white text more easily remembered? Hypothesis: If the text is colored, then the text is more

Varvara68 [4.7K]

Answer:

This question contains a lot of subsections. Please find the variables to each question below

Explanation:

Hypothesis is a testable explanation to a scientific question. It aims at proffering a testable solution to an observed problem. It usually goes in an IF, THEN format.

Dependent variable is the variable being measured in an experiment, while the independent variable is the variable that is manipulated or changed by the experimenter.

The control group is the group that does not receive the experimental treatment while constant is the variable that is kept unchanged for all groups in the experiment.

Based on this explanation, find the answers to the hypothesis, independent variable, dependent variable, constant, and control groups to each question.

2. Dependent variable: How easy it is to remember

Independent variable: Color of the text

Control: Group given Black and White text to read

Constants: Same text

3. Hypothesis: If the temperature is increased, THEN the speed of ants increases or move faster

Independent variable: TEMPERATURE

Dependent variable: SPEED OF ANTS

Control: Ants placed in room temperature

Constants: SAME KIND OF ANTS

4. Hypothesis: IF the pH of the soil is acidic or alkaline, THEN the growth of strawberries will be inhibited

Independent variable: pH of soil

Dependent variable: Growth of strawberries

Control: Strawberries grown in a Neutral pH soil

Constants: Same type of plants (strawberries)

5. Hypothesis: IF caffeine is taken, then the blood pressure will be increased or raised.

Independent variable: CAFFEINE

Dependent variable: BLOOD PRESSURE

Control: Group given no caffeine

Constants: Same amount of caffeine

6. Hypothesis: IF music is played, THEN the heart rate increases

Independent variable: MUSIC

Dependent variable: HEART RATE

Control: Groups placed where no music is played

Constants: Same type of music, same time music runs for etc.

7. Hypothesis: IF bleach is present/used, THEN bacteria will die

Independent variable: Bleach

Dependent variable: Death of bacteria

Control: Bacteria given no bleach

Constants: Same species of bacteria, Same type of bleach

3 0

3 years ago

How many atoms in chemical formula NaCl

musickatia [10]

Answer:

2 atoms

Explanation:

1 sodium atom + 1 chlorine atom = 2 atoms

4 0

3 years ago

How long does it take for a 12.62g sample of ammonia to heat from 209K to 367K if heated at a constant rate of 6.0kj/min? The me

Georgia [21]

First, consider the steps to heat the sample from 209 K to 367K.

1) Heating in liquid state from 209 K to 239.82 K

2) Vaporaizing at 239.82 K

3) Heating in gaseous state from 239.82 K to 367 K.

Second, calculate the amount of heat required for each step.

1) Liquid heating

Ammonia = NH3 => molar mass = 14.0 g/mol + 3*1g/mol = 17g/mol

=> number of moles = 12.62 g / 17 g/mol = 0.742 mol

Heat1 = #moles * heat capacity * ΔT

Heat1 = 0.742 mol * 80.8 J/mol*K * (239.82K - 209K) = 1,847.77 J

2) Vaporization

Heat2 = # moles * H vap

Heat2 = 0.742 mol * 23.33 kJ/mol = 17.31 kJ = 17310 J

3) Vapor heating

Heat3 = #moles * heat capacity * ΔT

Heat3 = 0.742 mol * 35.06 J / (mol*K) * (367K - 239.82K) = 3,308.53 J

Third, add up the heats for every steps:

Total heat = 1,847.77 J + 17,310 J + 3,308.53 J = 22,466.3 J

Fourth, divide the total heat by the heat rate:

Time = 22,466.3 J / (6000.0 J/min) = 3.7 min

Answer: 3.7 min

3 0

3 years ago