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3 years ago

An atom with an atomic number of 12 and a mass number of 25 can best be described by which of these

Chemistry

2 answers:

meriva3 years ago

8 0

A. An atom that contains 12 protons

Maslowich3 years ago

7 0

A. An atom that contains 12 protons and 13 neutrons.

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What is the structural formula for 2-methyl 3-ethylbutane?

ivann1987 [24]

Answer:

Explanation:

2-methyl-3-ethylpentane | C8H18 | ChemSpider.

Boiling Point: 115.3±7.0 °C at 760 mmHg

Molecular Formula: C8H18

Density: 0.7±0.1 g/cm 3

Enthalpy of Vaporization: 32.9±0.0 kJ/mol

4 0

3 years ago

a radioisotope has a half life of three hours how much of a 120g sample remains after 9 hours. what will the g amount be after 3

aksik [14]

$\huge\boxed{♔︎Answer♔︎}$

60g after 3 hours, 30g after 6 hours and 15g after 9 hours

Explanation:

Weight of the radioactive sample = 120g

half life time period = 3 hours

(a) The weight of sample after 3 hours

$\textsf{ No. of half lives} = \sf \cancel\frac{3}{3} = 1$

The fraction of sample left

$\sf { \frac{1}{2} }^{1} = \frac{1}{2}$

Mass of the sample left

$\sf \frac{1}{2} \times 120 = \cancel\frac{120}{2} = 60g$

60g of sample is left after 3 hours

(b) The weight of sample after 6 hours

$\textsf{ No. of half lives} = \sf \cancel\frac{6}{3} = 2$

The fraction of the sample left

$\sf { \frac{1}{2} }^{2} = \frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$

Mass of the sample left

$\sf \frac{1}{4} \times 120 = \cancel\frac{120}{4} = 30g$

30g of sample is left after 6 hours

$\textsf {No. of half lives} = \sf \cancel\frac{9}{3} = 3$

The fraction of sample left

$\sf { \frac{1}{2} }^{3} = \frac{1}{2} \times \frac{1}{2} \times \frac{1}{2} = \frac{1}{8}$

Mass of sample left

$\sf \frac{1}{8} \times 120 = \cancel \frac{120}{8} = 15g$

15g of sample is left after 9 hours.

3 0

2 years ago

What process at the surface of the Earth is part of the formation of sedimentary rocks?

OLga [1]

Answer:

Clastic sedimentary rocks are made up of pieces (clasts) of pre-existing rocks. Pieces of rock are loosened by weathering, then transported to some basin or depression where sediment is trapped. If the sediment is buried deeply, it becomes compacted and cemented, forming sedimentary rock.

please give brainliest

3 0

3 years ago

If all three metals were exposed to extremely high temperatures, which would be the last to melt?

Verdich [7]

Copper would be the last to melt because it has the highest melting point!

3 0

3 years ago

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Which natural polymer makes up paper? A. starch B. nylon C. wool D. rubber

eduard

Answer:

starch

Explanation:

7 0

3 years ago