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3 years ago

How many neutrons are probably in the nucleus of an element of atomic weight 197?

Chemistry

1 answer:

Ratling [72]3 years ago

4 0

Atomic weight = 197
symbol = Au
electrons = 79

neutrons = 197 - 79 = 118

<u>answer: E</u>

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Varvara68 [4.7K]

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3 years ago

What does the stonefish eat

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3 years ago

The rate of a certain reaction is given by the following rate law: rate Use this information to answer the question below. At a

AleksAgata [21]

Answer:

Initial rate of the reaction when concentration of hydrogen gas is doubled will be $3.2\times 10^6 M/s$ .

Explanation:

$N_2+3H_2\rightarrow 2NH_3$

Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

Initial rate of the reaction = R = $4.0\times 10^5 M/s$

$R = k\times [N_2][H_2]^3$

$4.0\times 10^5 M/s=k\times [N_2][H_2]^3$

The initial rate of the reaction when concentration of hydrogen gas is doubled : R'

$[H_2]'=2[H_2]$

$R'=k\times [N_2][H_2]'^3=k\times [N_2][2H_2]^3$

$R'=8\times k\times [N_2][H_2]^3$

$R'=8\times R=8\times 4\times 10^5 M/s=3.2\times 10^6 M/s$

Initial rate of the reaction when concentration of hydrogen gas is doubled will be $3.2\times 10^6 M/s$ .

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3 years ago

Lawrencium-262 has a half-life of 4 hr. How much of a 40 mg sample remains after 12 hours?

CaHeK987 [17]

Answer:

5 mg

Explanation:

If one half life is 4 hours, then 3 half lives is 12 hours.

This means that the sample will decay to 1/8 of its original amount.

So, the answer is 40(1/8) = 5 mg.

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1 year ago

Find the number of CoCl2 units present in a 0.78 mol sample.

stich3 [128]

$\qquad\qquad\huge\underline{{\sf Answer}}$

Here we go ~

1 mole of $\sf{ COCl_2}$ has 6.022 × 10²³ molecules of the given compound.

So, 0.78 mole of $\sf{COCl_2}$ will have ~

$\qquad \sf \dashrightarrow \: 0.78 \times 6.022 \times 10 {}^{23}$

$\qquad \sf \dashrightarrow \: \approx4.7 \times 10 {}^{23} \: \: \: molecules$

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2 years ago