A.
25km x 10^3m/1km x 1cm/10^-2m
cancel out km and m left with cm
Answer:
3.97 M
Explanation:
Given data:
Initial volume V₁ = 318 mL
Initial molarity M₁ = 5.75 M
New volume V₂= 461 mL
New concentration M₂= ?
Solution:
New volume V₂= 143 mL+ 318 mL
New volume V₂= 461 mL
Formula:
M₁V₁ = M₂V₂
M₂ = M₁V₁ / V₂
M₂ = 5.75 M × 318 mL / 461 mL
M₂ = 1828.5 M. mL/ 461 mL
M₂ = 3.97 M
Hey there!
A half-life means after a certain amount of time, half of that substance will have decayed after that time.
An equation for exponential decay is the following:
y = a(1 - b)ⁿ
Where a is the original amount, b is the rate of decay, and n is time.
1000 is about 0.3 of a half life, 1000 divided by 138 days (3312 hours) is approximately 0.3.
Let's plug in values to that equation:
y = 321(1 - 0.5)^(0.3)
Simplify.
y = 260.73
There will be 260.73mg of polonium-210 remaining after 1000 hours.
Hope this helps!
Answer:
133.74 L
Explanation:
First we <u>convert the given pressures and temperatures into atm and K</u>, respectively:
- 750.0 Torr ⇒ 750/760 = 0.9868 atm
- 20°C ⇒ 20+273.16 = 293.16 K
- 40°C ⇒ 40+273.16 = 313.16 K
Then we<u> use the PV=nRT formula to calculate the number of moles of helium in the balloon</u>, using<em> the data of when it was on the ground</em>:
- 0.9868 atm * 8.50 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 293.16 K
Then, knowing the value of n, we <u>use PV=nRT once again, this time to calculate V</u> using <em>the data of when the balloon was high up:</em>
- 0.550 atm * V = 2.866 mol * 0.082 atm·L·mol⁻¹·K⁻¹ * 313.16 K
Answer: 8 dots would be needed to represent the outer electrons for an atom of neon in an electron dot diagram.
Explanation:
Electron-dot diagram is also known as Lewis-dot structure. It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule. The valence electrons are represented by 'dot'.
As atomic number of neon is 10 and we know that neon has 10 electrons with electronic configuration of 2,8 and thus has '8' valence electrons.
Therefore, the total number of valence electrons is 8 and 8 dots would be needed to represent the outer electrons for an atom of neon in an electron dot diagram.
