1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
hodyreva [135]
2 years ago
9

Which of the following elements has two valence electrons?

Chemistry
1 answer:
lara31 [8.8K]2 years ago
5 0
Beryllium, Magnesium, Calcium....etc have two valence electrons
You might be interested in
Radioactive cobalt-60 is frequently used in treating cancer. It took 24 years for a 10 gram sample to decay to 0.625 grams. What
-BARSIC- [3]

Answer:

Half life is 6 years.

Explanation:

T½ = In2 / λ

Where λ = decay constant.

But N = No * e^-λt

Where N = final mass after a certain period of time

No = initial mass

T = time

N = 0.625g

No = 10g

t = 24 years

N = No* e^-λt

N / No = e^-λt

λ = -( 1 / t) In N / No (inverse of e is In. Check logarithmic rules)

λ = -(1 / 24) * In (0.625/10)

λ = -0.04167 * In(0.0625)

λ = -0.04167 * (-2.77)

λ = 0.1154

T½ = In2 / λ

T½ = 0.693 / 0.1154

T½ = 6.00 years.

The half life of radioactive cobalt-60 is 6 years

5 0
2 years ago
What is The pH and pOH of a 1.00x10-3M solution of CH3COOH (Ka=1.75x10-5) ?
zaharov [31]

Answer:

<h2>pH = 3.9</h2><h2>pOH = 10.1</h2>

Explanation:

Since CH _ 3COOH is a weak acid to find the pH of CH _ 3COOH we use the formula

pH =  -  \frac{1}{2}   log(Ka)  -  \frac{1}{2}  log(c)

where

Ka is the acid dissociation constant

c is the concentration

From the question

Ka of CH _ 3COOH = 1.75 × 10^-5

c = 1.00 × 10-³M

Substitute the values into the above formula and solve for the pH

That's

pH =  \frac{1}{2} ( -  log(1.75 \times {10 }^{ - 5} -  log(1.00 \times  {10}^{ - 3} )  )  \\   =  \frac{1}{2} (4.757  + 3) \\  =  \frac{1}{2}  \times 7.757) \\  = 3.8785 \:  \:  \:  \:  \:  \:  \:  \:

We have the answer as

<h3>pH = 3.9</h3>

To find the pOH we use the formula

pH + pOH = 14

pOH = 14 - pH

pOH = 14 - 3.9

We have the answer as

<h3>pOH = 10.1</h3>

Hope this helps you

4 0
3 years ago
State which statement is a physical change or a chemical change:
Oliga [24]

Answer:

Physical change: A,C ,D, F, H, I

Chemical Change: B, E, G, J, K

4 0
3 years ago
Why do waves move faster at higher temperatures and in a solid phase?
podryga [215]
<span>There is more energy and the particles are closer together.</span>
7 0
3 years ago
Read 2 more answers
Water covers over 70% of planet Earth and most of the water is salt water. Which
Serga [27]

Answer:

D. 4

Explanation:

6 0
3 years ago
Other questions:
  • What is number one I need help
    9·1 answer
  • When exchanging information<br><br> with anyone involved in the<br><br> collision, you should
    13·1 answer
  • How would Mg change to gain a noble gas structure?<br><br> lose 2 electrons<br> gain 6 electrons
    10·2 answers
  • What is reactant, atom, product, and molecule
    8·1 answer
  • A solution is composed of 85.5 wt% methanol in water. Find the mol fraction of methanol in the solution.
    14·1 answer
  • Which of the following best defines a scientific law?
    15·2 answers
  • What do the digestive and excretory systems have in common?
    9·1 answer
  • Taxol is a potent chemotherapeutic agent (isolated from the Pacific Yew tree) which is especially effective against ovarian canc
    13·1 answer
  • HELPPPPP!!!!!!!!!!!!!!!!!!!!!!!!!!!! 30 POINTS!!!!!!!!!!!!!!
    13·2 answers
  • 25.0 mL of an LiOH solution were titrated with 29.15 mLof a 0.205 M H3PO4 solution to reach the equivalence point. What is the m
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!