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2 years ago

1. Which of these is the basic unit of mass?

Chemistry

2 answers:

jeka57 [31]2 years ago

7 0

1.)B 2.)C 3.)A 4.)B 5.)C

Juli2301 [7.4K]2 years ago

4 0

1) the basic unit of mass (SI unit) is Kg

2) the amount of matter in an object is known as density, infact the amount of matter in a unit volume is density

3) We can measure the mass with a balance

Burette: for volume

rule : for length

graduated cylinder : for volume

4) Weight is measure of force of gravity on a matter

5) the density of water = 1 g / mL at 4 C

so mass of 1 mL of water will be equal to 1 gram

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2 years ago

A sample of calcium phosphate was found to have a mass of 125.3 g. How many molecules were contained in the sample?

Viktor [21]

The answer for the following problem is mentioned below.

Therefore number of molecules(N) present in the calcium phosphate sample are 19.3 × 10^23 molecules.

Explanation:

Given:

mass of calcium phosphate ( $Ca_{3}(PO_{4} )_{2}$ ) = 125.3 grams

We know;

molar mass of calcium phosphate ( $Ca_{3}(PO_{4} )_{2}$ ) = (40×3) + 3 (31 +(4×16))

molar mass of calcium phosphate ( $Ca_{3}(PO_{4} )_{2}$ ) = 120 + 3(95)

molar mass of calcium phosphate ( $Ca_{3}(PO_{4} )_{2}$ ) = 120 +285 = 405 grams

We also know;

No of molecules at STP conditions( $N_{A}$ ) = 6.023 × 10^23 molecules

To solve:

no of molecules present in the sample(N)

We know;

$\frac{m}{M} =\frac{N} }{}$ N÷ $N_{A}$

$\frac{405}{125.3}$ = $\frac{N}{6.023*10^23}$

N =(405×6.023 × 10^23) ÷ 125.3

N = 19.3 × 10^23 molecules

Therefore number of molecules(N) present in the calcium phosphate sample are 19.3 × 10^23 molecules

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3 years ago

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Explanation:

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2 years ago