Answer:
C. Fill two identical pots with equal volumes of salt water and tap water and use a stopwatch to determine the time it takes each pot to boil.
Explanation:
<u>A) is incorrect</u> because Peter should have the same testing environment for both of his experiments.
He should choose the same method of boiling the salt water and tap water because the stovetop and the microwave could also affect the results and make them unreliable.
<u>B) is incorrect</u> because Peter should not estimate the time it takes the salt water and tap water to boil.
Peter should measure and record the amount of time that it takes these substances to boil in order to have an accurate, valid experimental thesis.
<u>C) is correct</u> because Peter uses the same volume of salt water and tap water, fills them into two identical pots, and uses a stopwatch to determine the amount of time it takes each pot to boil.
The stopwatch makes the experiment more valid and accurate compared to the previous methods, and the identical pots and amounts of water help this experiment become even more precise.
<u>D) is incorrect</u> because the variables in the experiment are not controlled amounts and will therefore produce an inaccurate and invalid experiment.
Answer:
Photosynthesis is the pocess by which green plants make their own food.
b. sunlight, glucose, water, altra-violet ray as catalyst
Answer:
273m/s
Explanation: <u>Root</u> <u>Mean</u> <u>Square</u> <u>Speed</u> of an atom or molecule is the speed of a particle in a gas. It is the average speed a particle in a gas can have.
It can be calculated:



m is mass of one atom or molecule in kg.
An atom of Arsenic sublimes at 614°C. Converting to Kelvin:
T = 614 + 273 = 887K
Molecular mass of As4 is approximately 0.3kg.
kg
Calculating Root mean square speed :


v = 273m/s
<u>The root mean square speed of As4 is approximately </u><u>273m/s</u><u>.</u>
I believe the answer is all of the above.