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4 years ago

You need to do a research paper on global warming which of the following would be a reliable source for the information you need

Chemistry

1 answer:

Ahat [919]4 years ago

4 0

C is obvious because no other choice has any closer answer

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A certain substance X has a normal freezing point of -6.4 C and a molal freezing point depression constant Kf= 3.96 degrees C.kg

Brut [27]

Answer: $1.0\times 10^2g$

Explanation:

Depression in freezing point is given by:

$\Delta T_f=i\times K_f\times m$

$\Delta T_f=T_f^0-T_f=(-6.4-(13.6))^0C=7.2^0C$ = Depression in freezing point

i= vant hoff factor = 1 (for non electrolyte like urea)

$K_f$ = freezing point constant = $3.96^0C/m$

m= molality

$\Delta T_f=i\times K_f\times \frac{\text{mass of solute}}{\text{molar mass of solute}}\times \text{weight of solvent in kg}}$

Weight of solvent (X)= 950 g = 0.95 kg

Molar mass of non electrolyte (urea) = 60.06 g/mol

Mass of non electrolyte (urea) added = ?

$7.2=1\times 3.96\times \frac{xg}{60.06 g/mol\times 0.95kg}$

$x=1.0\times 10^2g$

Thus $1.0\times 10^2g$ urea was dissolved.

8 0

4 years ago

Which of the following is evidence of a physical change?

patriot [66]

The answer is >>>>
C) decomposing

8 0

3 years ago

Read 2 more answers

Which statement about caves and polluted groundwater is true? A. Cave rock neutralizes the pollutants in the groundwater. B. Wel

zvonat [6]

Cave rock neutralizes pollutants in groundwater.

3 0

3 years ago

True or False: When converting grams to moles, "1mol" should be on the top of the

WINSTONCH [101]

Answer:

True

Explanation:

The grams are on the bottom of the conversion factor to cancel out the unit and convert to mol.

6 0

4 years ago

svetlana [45]

Answer: $1.6\times 10^4$

Explanation:

Scientific notation is defined as the representation of expressing the numbers that are too big or too small and are represented in the decimal form with one digit before the decimal point times 10 raise to the power.

For example : 5000 is written as $5.0\times 10^3$

In division , the result would contain the same number of significant digits as there in the least precise number , thus the answer would have 2 significant digits.

$\frac{1.248\times 10^{-2}}{7.8\times 10^{-7}}=1.6\times 10^4$

5 0

4 years ago