Why does opening the air valve of a tire at a constant temperature decrease the pressure

The half-life of a radioactive isotope is the amount of time it takes for a quantity of that isotope to decay to one half of its

Sedaia [141]

Radio active decay reactions follow first order rate kinetics.

a) The half life and decay constant for radio active decay reactions are related by the equation:

$t_{\frac{1}{2}} =$ $\frac{ln 2}{k}$

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

Where k is the decay constant

b) Finding out the decay constant for the decay of C-14 isotope:

$Decay constant (k) = \frac{0.693}{t_{\frac{1}{2}}}$

$k = \frac{0.693}{5230 years}$

$k = 1.325 * 10^{-4} yr^{-1}$

c) Finding the age of the sample :

35 % of the radiocarbon is present currently.

The first order rate equation is,

$[A] = [A_{0}]e^{-kt}$

$\frac{[A]}{[A_{0}]} = e^{-kt}$

$\frac{35}{100} = e^{-(1.325 *10^{-4})t}$

$ln(0.35) = -(1.325 *10^{-4})(t)$

t = 7923 years

Therefore, age of the sample is 7923 years.

3 0

3 years ago

What is national flower of nepal?

Vanyuwa [196]

Answer:

national flower : Rhododendron

national animal : cow

national bird : Himalayan Monal

4 0

2 years ago

One difference between molecular formula and molecular weight.

jek_recluse [69]

Answer: The formula mass (formula weight) of a molecule is the sum of the atomic weights of the atoms in its empirical formula. The molecular mass (molecular weight) of a molecule is its average mass as calculated by adding together the atomic weights of the atoms in the molecular formula.

Hope this helps.... Stay safe and have a great weekend!!!!! :D

3 0

2 years ago

If you are given a 0. 31 g piece of sodium metal to react with water, how many moles of hcl would it take to neutralize the sodi

Sphinxa [80]

The moles of HCl to neutralize the sodium hydroxide produced is 0.0135 mole.

Neutralization or neutralization is a chemical response wherein an acid and a base react quantitatively with each other. In a reaction in water, neutralization outcomes in there being no excess of hydrogen or hydroxide ions gift in the answer.

calculation:-

2Na + 2H₂O -----> 2NaOH + H₂

2 mol or 46g of Na produces 80 grams of NaOH

∴ 0.31 g of Na will produce = 80/46 × 0.31

= 0.54 gram of NaOH.

mol of NaOH = 0.54/40

= 0.0135

Since both Hcl and NaOH have the same valance factor,

1 mole NaOH is needed to neutralize 1 mol HCl

∴ 0.0135 mole of NaOH will need = 0.0135 mole of HCl

mass = 0.0135 × 36.5

= 0.493 grams of HCL.

Learn more about neutralizing here:-brainly.com/question/23008798

#SPJ4

4 0

9 months ago

Which is heavier einsteinium (Es) or europium (Eu)

Maksim231197 [3]

Answer:

Einsteinium is heavier

Explanation:

Atomic weight is what we are referring to when figuring out how heavy an element is and is measured in amu (atomic mass units)

(This is also the same as the molar mass how heavy 6.022 x 10^23 atoms of a substance or element is which is measured in grams)

The atomic weight of an element can be found on a periodic table.

Europium has an atomic mass of approximately 152 amu (atomic mass units)

Einsteinium has an atomic mass of approximately 252 amu.

Einsteinium has a higher atomic weight so it's heavier.

There's another easier way of going about it where you don't even have to think about the actual number and basically just look at the element's atomic number and position on the periodic table.

Eu is 63

Es is 99

As the atomic number increases on the periodic table this means it's number of protons is greater.

Protons lie in the nucleus which has most of the atom's weight so the more protons the heavier it is.

Einsteinium has a higher atomic number meaning it has more protons so we can assume it's the heavier one.

Hope this helps!

3 0

3 years ago