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Norma-Jean [14]
3 years ago
12

An atom has a mass number of 9 and 5 neutrons. What is its atomic number? A 19 B. 14 O c.4 D. 11 SN​

Chemistry
2 answers:
nika2105 [10]3 years ago
5 0

Answer:

\boxed {\boxed {\sf C. \ 4}}

Explanation:

First, define some important terms.

  • Mass number: the sum of the nucleons (protons and neutrons)
  • Atomic number: the number of protons

We know the mass number is 9. So, the sum of protons and neutrons is 9.

  • mass \ number =9
  • protons + neutrons = 9

We also know the atoms has 5 neutrons. Therefore, the rest must be protons.

  • protons + 5 \ neutrons =9

Subtract the 5 neutrons from the overall mass number of 9.

  • protons = 9- 5 \ neutrons \\
  • protons=4

There are 4 protons, so the atomic number is also <u>4</u>. This atom is beryllium.

butalik [34]3 years ago
4 0

Answer:

C. 4

Explanation:

the mass is the number of neutrons and Protons. so if you have 5 neutrons that means the rest are Protons... and the number of Protons is the Atomic number meaning the Element number... Beryllium is the element :)

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Draw the most stable resonance structure for the intermediate in the electrophilic aromatic bromination of aniline, anisole, and
ASHA 777 [7]

Answer:

Here's what I get

Explanation:

(a) Intermediates

The three structures below represent one contributor to the resonance-stabilized intermediate, in which the lone pair electrons on the heteroatom are participating (the + charge on the heteroatoms do not show up very well).

(b) Relative Stabilities

The relative stabilities decrease in the order shown.

N is more basic than O, so NH₂ is the best electron donating group (EDG) and will best stabilize the positive charge in the ring. However, the lone pair electrons on the N in acetanilide are also involved in resonance with the carbonyl group, so they are not as available for stabilization of the ring.

(c) Relative reactivities

The relative reactivities would be

C₆H₅-NH₂ >  C₆H₅-OCH₃ > C₆H₅-NHCOCH₃

4 0
3 years ago
Moraines left by glaciers are different from deposits left by rivers because the rocks left behind are _____.
12345 [234]

Explanation:

unorganized and unsorted i think this is the answer

7 0
3 years ago
Acetone is one of the most important solvents in organic chemistry. It is used to dissolve everything from fats and waxes to air
Yanka [14]

Answer: a. 79.6 s

b. 44.3 s

c. 191 s

Explanation:

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 = age of sample

a = let initial amount of the reactant  

a - x = amount left after decay process  

a) for completion of half life:

Half life is the amount of time taken by a radioactive material to decay to half of its original value.

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

t_{\frac{1}{2}}=\frac{0.693}{8.7\times 10^{-3}s^{-1}}=79.6s

b) for completion of 32% of reaction  

t=\frac{2.303}{k}\log\frac{100}{100-32}

t=\frac{2.303}{8.7\times 10^{-3}}\log\frac{100}{68}

t=44.3s

c) for completion of 81 % of reaction  

t=\frac{2.303}{k}\log\frac{100}{100-81}

t=\frac{2.303}{8.7\times 10^{-3}}\log\frac{100}{19}

t=191s

4 0
3 years ago
What is the Nobel gas notation for selenium​
seraphim [82]

Answer:

Se =[Ar] 3d¹⁰ 4s² 4p⁴

Explanation:

The noble gas notation is used for the shortest electronic configuration of other periodic table elements.

For example:

The atomic number of Argon is 18, and its electronic configuration is,

Ar₁₈ = 1s² 2s² 2p⁶ 3s² 3p⁶

The atomic number of selenium is 34, its electronic configuration is,

Se₃₄ = 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁴

By using the noble gas notation, electronic configuration of selenium can be written is shortest form.

Se =[Ar] 3d¹⁰ 4s² 4p⁴

This electronic configuration is also called abbreviated electronic configuration.

5 0
3 years ago
What is Oxidation state of sulphur in Na2S4O6?Help me..​
quester [9]

Answer:

oxidation state of sulphur=x

Explanation:

Na2S4O6=2[+1]+4x+6[-2]=0

                 +2+4x-12=0

                     4x-10=0

                           4x=10

                            x=10/4=2.5

6 0
3 years ago
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