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
Tasya [4]
3 years ago
10

Need these 2 answered asap pls

Chemistry
1 answer:
Kitty [74]3 years ago
3 0

Answer:

im not a brain wiz but i think 20

Explanation:

You might be interested in
Neon has 2 isotopes. Neon-20 has a mass of 19:992 amu and
Alenkinab [10]

Answer:

20.0928.

Explanation:

The average atomic mass is (90 * 19.992 + 10* 21) / 100

= 20.0928.

6 0
3 years ago
Which observation does not indicate that a chemical reaction has occurred?
castortr0y [4]

Answer:

change in the total mass of substances

6 0
3 years ago
A very old tree limb contains an amount of carbon-14 that is approximately 1/8 of the current atmospheric 14C levels.. Calculate
Tomtit [17]

A.       The radioactive decay equation is N = N0e^{-ln(2)*t/T }

where T is the half-life (5730 years), N0 is the number of atoms at time t = 0 and N is the number at time t.

Rewriting this as:

(N/N0) = e^{-ln(2)*t/T }

Since N = (1/8) N0 and substituting known values:

1/8 = e^{-ln(2)*t/5730}

Taking ln of both sides:

ln(1/8)= -ln(2)*t/5730

t = - 5730 * ln(1/8) / ln (2)

t = 17,190 years

The tree was cut down 17,190 years ago.

B.   N0 = 1,500,000 carbon-14 atoms

Since N = (1/8) N0

N = 187,500 carbon atoms left

3 0
3 years ago
Hydrogen gas and fluorine gas will react to form hydrogen fluoride gas. What is the standard free energy change for this reactio
Marta_Voda [28]

Answer:

\Delta G=-541.4kJ/mol

Explanation:

Hello there!

In this case, according to the given information, it turns out firstly necessary to write out the described chemical reaction as shown below:

H_2+F_2\rightarrow 2HF

Now, we set up the expression for the calculation of the standard free energy change, considering the free energy of formation of each species, specially those of H2 and F2 which are both 0 because they are pure elements:

\Delta G=2\Delta G_f^{HF}-(\Delta G_f^{H_2}+\Delta G_f^{F_2})\\\\\Delta G=2*-270.70kJ/mol-(0kJ/mol+0kJ/mol)\\\\\Delta G=-541.4kJ/mol

Regards!

4 0
3 years ago
A drinking water plant adds 500 grams of fluoride to a water tank containing 500,000 liters of drinking water. what is the conce
nlexa [21]
Answer is: <span>concentration of fluoride in the water in parts-per-million is 1 ppm.
</span>Parts-per-million (10⁻⁶) is<span> present at one-millionth of a </span>gram per gram of sample solution, f<span>or example mg/kg.
</span>m(fluoride) = 500 g · 1000 mg/g = 500000 mg.
m(water) = d(water) · V(water).
m(water) = 1 kg/L · 500000 L.
m(water) = 500000 kg.
arts-per-million = 500000 mg ÷ 500000 kg = 1 mg/kg = 1 ppm.
5 0
3 years ago
Other questions:
  • Been struggling with this question for a while, some help will be appreciated :)
    5·1 answer
  • How can pH go high over time
    7·2 answers
  • A compound is 87.1% ag &amp; 12.9% s. find the empirical formula
    6·1 answer
  • Write the reaction responsible for the solution being basic. Do not include spectator ions. With NaF being the salt that produce
    10·1 answer
  • Which substance has a molar mass of 33.99 g/mol?
    14·1 answer
  • What can you determine about an element if you only know its group number on the periodic table?
    6·2 answers
  • Give the major product formed when phenol is heated with concentrated H2SO4 and SO3. (There is more than one correct answer, but
    5·1 answer
  • How many miles of Fe are in 11.8 g of Fe
    12·2 answers
  • Explain when the term vapor should be used to describe the gas phase.
    8·1 answer
  • The burning characteristics of a gasoline can be improved by converting the octane it contains into isooctane. This conversion r
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!