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PtichkaEL [24]
3 years ago
8

Which element has the same number of valence electrons as hydrogen (H)? A. helium (He). . B. oxygen (O). . C. nitrogen (N). . D.

lithium (Li).
Chemistry
2 answers:
velikii [3]3 years ago
7 0

Answer : The correct option is (D) lithium (Li).

Explanation :

Hydrogen is the element which belong to period 1. The atomic number of hydrogen is, 1

The electronic configuration of hydrogen is, 1s^1

The number of valence electrons present in hydrogen is, 1.

(A) Helium is the element which belong to period 1. The atomic number of helium is, 2

The electronic configuration of helium is, 1s^2

The number of valence electrons present in helium is, 2.

(B) Oxygen is the element which belong to period 2. The atomic number of oxygen is, 8

The electronic configuration of oxygen is, 1s^22s^22p^4

The number of valence electrons present in oxygen is, 6.

(C) Nitrogen is the element which belong to period 2. The atomic number of nitrogen is, 7

The electronic configuration of nitrogen is, 1s^22s^22p^3

The number of valence electrons present in nitrogen is, 5.

(D) Lithium is the element which belong to period 2. The atomic number of lithium is, 3

The electronic configuration of lithium is, 1s^22s^1

The number of valence electrons present in lithium is, 1.

From this we conclude that the lithium element has the same number of valence electrons as hydrogen.

Hence, the correct option is (D) lithium (Li).

deff fn [24]3 years ago
4 0
Li is in group 1 so it has same number of valence electrons as hydrogen.
hope it helps.
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25.0 mL of an HBr solution were titrated with 29.15 mL of a 0.205 M LiOH solution to reach the equivalence point. What is the mo
krok68 [10]

HBr reacts with LiOH and forms LiBr and H₂O as the products. The balanced reaction is

LiOH(aq) + HBr(aq) → LiBr(aq) + H₂O(l)

Molarity (M) = moles of solute (mol) / volume of the solution (L)

Molarity of LiOH = 0.205 M

Volume of LiOH = 29.15 mL = 29.15 x 10⁻³ L

Hence,

moles of LiOH = molarity x volume of the solution

= 0.205 M x 29.15 x 10⁻³ L

= 5.97575 x 10⁻³ mol

The stoichiometric ratio between LiOH and HBr is 1 : 1.

Hence,

moles of HBr in 25.0 mL = moles of LiOH added

= 5.97575 x 10⁻³ mol

Hence, molarity of HBr = 5.97575 x 10⁻³ mol / 25.00 x 10⁻³ L

= 0.23903 M

≈ 0.239 M

Hence, the molarity of the HBr is 0.239 M.

6 0
4 years ago
Read 2 more answers
On left, C l with 2 black dots each above, left, and below and 1 black dot right. On the right, C l with 2 black dots each above
laila [671]

Answer:

Chlorine has seven valence electrons

Explanation:

The dot structure of chlorine was just described in the question. The two dots above, below and by the left are three lone pairs making a total of six electrons. There is another one black dot indicating one electron.

This one electron on both chlorine atoms combine to form the chlorine molecule Cl2.

5 0
3 years ago
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What is the half-life of iron-59, a radioisotope used medically in the diagnosis of anemia, if a sample with an initial decay ra
Y_Kistochka [10]
1) Data:

<span>initial decay rate, No =16,800 disintegrations/min

final decay rate, Nf = 10,860 disintegrations/min

t = 28.0 days

t half-life =?

2) Formulas

Radioactive disintegration =>

Nt = No * e ^ (-kt)

t half-life = ln (2) / k

3) Solution

From Nt = No * e^ (-kt) =>

Nt / No = e ^ (-kt)

=> -kt = ln (Nt / No)

=> kt = ln (No/Nt)

=> k = ln (No / Nt) / t

=> k = ln (16,800 / 10,860) / 28 days = 0.01558 days^ -1

From t half-life = ln(2) / k

t half-life = ln(2) / (0.01558 days^-1) = 44.5 days.

Answer: 44.5 days.


</span>
8 0
3 years ago
Substance _____ involves repeated, harmful use of a substance whereas substance _____ is a physical and/or psychological addicti
alina1380 [7]
Substance abuse... Substance addiction or dependence??
6 0
4 years ago
The density of an object is 7.3 g/mL and the volume is 0.94<br> mL. What is the mass of the object?
Alex777 [14]

Answer:

<h3>The answer is 6.86 g</h3>

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

<h3>mass = Density × volume</h3>

From the question

volume = 0.94 mL

density = 7.3 g/mL

We have

mass = 7.3 × 0.94 = 6.862

We have the final answer as

<h3>6.86 g</h3>

Hope this helps you

5 0
3 years ago
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