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4 years ago

What is science? Why do you think science is important?

Chemistry

1 answer:

ryzh [129]4 years ago

3 0

Answer:

Science is the study of the physical or material world. Science is important because it can answer questions about new ideas and can advance technologies

Explanation:

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Please help! it’s due date is in a few minutes

Licemer1 [7]

Answer:

40'0'

Explanation:

X is smaller than |-40|

7 0

2 years ago

There are seven major levels of classification. Kingdom and Phylum are just two of the levels. Which of the following are also m

kumpel [21]

A) The class and C) Family would be the only accurate option. Here are the levels from largest to smallest: <span>kingdom, phylum, class, order, family, genus and species.</span>

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3 years ago

What a three of the signs of an allergic reaction to iv t-pa?

Anna007 [38]

Look out for angioedema (like hives but a deeper swelling due to an allergic reacrion), bleeding (such as intracranial, gastrointestinal and genitourinal hemorrhaging) and adverse reactions to drugs. Nausea, blood pressure spikes, severe headaches, acute hypertsnsion, etc are other signs of negative reacrions to iv t-pa as well.

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3 years ago

A sample of CaCO3 (molar mass 100. g) was reported as being 30. percent Ca. Assuming no calcium was present in any impurities, c

natka813 [3]

Answer:

Approximately 75%.

Explanation:

Look up the relative atomic mass of Ca on a modern periodic table:

Ca: 40.078.

There are one mole of Ca atoms in each mole of CaCO₃ formula unit.

The mass of one mole of CaCO₃ is the same as the molar mass of this compound: $\rm 100\; g$ .
The mass of one mole of Ca atoms is (numerically) the same as the relative atomic mass of this element: $\rm 40.078\; g$ .

Calculate the mass ratio of Ca in a pure sample of CaCO₃:

$\displaystyle \frac{m(\mathrm{Ca})}{m\left(\mathrm{CaCO_3}\right)} = \frac{40.078}{100} \approx \frac{2}{5}$ .

Let the mass of the sample be 100 g. This sample of CaCO₃ contains 30% Ca by mass. In that 100 grams of this sample, there would be $\rm 30 \% \times 100\; g = 30\; g$ of Ca atoms. Assuming that the impurity does not contain any Ca. In other words, all these Ca atoms belong to CaCO₃. Apply the ratio $\displaystyle \frac{m(\mathrm{Ca})}{m\left(\mathrm{CaCO_3}\right)} \approx \frac{2}{5}$ :

$\begin{aligned} m\left(\mathrm{CaCO_3}\right) &= m(\mathrm{Ca})\left/\frac{m(\mathrm{Ca})}{m\left(\mathrm{CaCO_3}\right)}\right. \cr &\approx 30\; \rm g \left/ \frac{2}{5}\right. \cr &= 75\; \rm g \end{aligned}$ .

In other words, by these assumptions, 100 grams of this sample would contain 75 grams of CaCO₃. The percentage mass of CaCO₃ in this sample would thus be equal to:

$\displaystyle 100\%\times \frac{m\left(\mathrm{CaCO_3}\right)}{m(\text{sample})} = \frac{75}{100} = 75\%$ .

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3 years ago

PLEASE MATCH AND LABEL THEM A TO E ILL CASHAPP YOU MONEY.

Aloiza [94]

41) c

42) e

43) b

44) d

45) a

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3 years ago