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3 years ago

An area where material from deep within Earth's mantle rises to the crust and melts to form magma is called a

Chemistry

1 answer:

AnnyKZ [126]3 years ago

6 0

Answer:

centro of the eqrhtjrurjfjrnfbfn

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The mass number of an atom is 15, and its atomic number is 7. The atom probably has... 8 neutrons in the nucleus. about as much

Artist 52 [7]

Answer: Option (a) is the correct answer.

Explanation:

Atomic number is the sum of only total number of protons present in an element. Whereas mass number is the sum of total number of both protons and neutrons present in an element.

For example, given atom has mass number as 15 and its atomic number is 7.

Therefore, number of neutrons present in it will be calculated as follows.

Mass number = no. of protons + no. of neutrons

15 = 7 + no. of neutrons

no. of neutrons = 15 - 7

= 8

Thus, we can conclude that the given atom contains 8 neutrons in the nucleus.

3 0

3 years ago

PROJECT: KITCHEN TOOLS

docker41 [41]

Answer:

Explanation:2+2=4

7 0

3 years ago

For each of the following units and concentration values, mention if they are parts per million (ppm), parts per billion (ppb) o

arsen [322]

Answer:

a) ppm

b) ppm

c) ppb

d) ppt

e) ppb

Explanation:

a) You know that 1000 g are 1 kg, and 1000 kg are 1 ton, so (1000)*(1000) g are 1 ton, so 1,000,000 grams are one ton.

b) 1000 mg are 1 g, and 1000 g are 1 liter, so 1,000,000 grams are one liter.

c) You know that 1000 ug are 1 mg, so with the b), we just need to multiply the answer by 1000, so 1,000,000,000 ug are 1 liter.

d) The same as c, 1000 ng are 1 mg. So we are talkinf of ppt.

e) 1000 mg are 1 g. And 1000 g are 1 kg, then 1000 kg are one ton. So 1,000,000,000 mg are one ton.

7 0

3 years ago

One of the radioactive isotopes used in medical treatment or analysis is chromium-51. The half-life of chromium-51 is 28 days. H

Goryan [66]

Answer : The time required for decay is, 84 days.

Explanation :

Half-life of chromium-51 = 28 days

First we have to calculate the rate constant, we use the formula :

$k=\frac{0.693}{t_{1/2}}$

$k=\frac{0.693}{28\text{ days}}$

$k=0.0248\text{ days}^{-1}$

Now we have to calculate the time required for decay.

Expression for rate law for first order kinetics is given by:

$t=\frac{2.303}{k}\log\frac{a}{a-x}$

where,

k = rate constant

t = time taken by sample = ?

a = let initial activity of the sample = 100

a - x = amount left after decay process = 12.5

Now put all the given values in above equation, we get

$t=\frac{2.303}{0.0248}\log\frac{100}{12.5}$

$t=83.9\text{ days}\approx 84\text{ days}$

Therefore, the time required for decay is, 84 days.

7 0

3 years ago

How many particles are in one mole substance

Karolina [17]

Avogadro's number is defined as the number of elementary particles (molecules, atoms, compounds, etc.) per mole of a substance. It is equal to 6.022×1023 mol-1 and is expressed as the symbol NA.

6 0

3 years ago

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