Chemistry, 18.08.2020 14:01 sarah8479

Dominick and eva are using the same type of stopwatches to measure the time it takes for a chemical reaction to occur. They can use the same stopwatch to measure the time.

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Answer from: clarissajimenez27

They did not repeat their tests multiple times.

Explanation:

It may seem that the question is incomplete. The complete question is as below: Dominic and Eva are using the same type of stopwatches to measure the time it takes for a chemical reaction to occur. They each use the same stopwatch to measure the time. These are their results:

Dominic: 78 seconds

Eva: 81 seconds

Why are their results unreliable and can lead to a pseudoscientific claim?

They did not repeat their tests multiple times.

They used the same type of stopwatch.

They did not change the reactants in their chemical reactions.

Only one person should have collected the data.

Dominic and Eva's results are unreliable and can lead to a pseudoscientific claim because they did not repeat their tests multiple times.

Repeating the test multiple times and finding the average of the measurement will minimize the chance of having error in the measurement and improve the accuracy of the outcome.

Thus, without repeated measurement, the reliability and the validity of the measurement would be in doubt.

Answer from: Quest

under a microscope, cancer cells may look very different from normal cells. they often have different sizes and some may be larger than normal while others are smaller. cancer cells are often abnormally shaped and the control centre of the cell (the nucleus) may have an abnormal appearance.

i think? ?

Answer from: Quest

$\frac{239}{94}pu+\frac{1}{0}n ====> \frac{y}{z}x+\frac{134}{54}xe+3\frac{1}{0}$

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137 subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54 subtract 54 from both sides.

40 = z

answer

$\frac{103}{40}x=\frac{103}{40}zr$

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