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aivan3 [116]
3 years ago
6

A radioactive substance used in nuclear weapons decays at the rate of 3.33.3​% per year. calculate the​ half-life of the radioac

tive substance.
Chemistry
1 answer:
mylen [45]3 years ago
3 0
The amount of substance that is present after t years given that the half-life of the substance is h is calculated through the equation,

   A(t) = A(o)(0.5^t/h)

If after a year, the rate of decay is equal to 33.3% then,

   A(t)/A(o) = (1/3) = 0.5^(1/h)

The value of h from the equation is 0.63 years. 

Answer: 0.63 years
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A container of gas is initially at 0.25 atm and 0 ˚C. What will the pressure be at 125 ˚C?
Pani-rosa [81]

Answer:

0.37atm

Explanation:

Given parameters:

Initial pressure  = 0.25atm

Initial temperature  = 0°C  = 273K

Final temperature  = 125°C  = 125 + 273  = 398K

Unknown:

Final pressure  = ?

Solution:

To solve this problem, we use a derivative of the combined gas law;

           \frac{P1}{T1}  = \frac{P2}{T2}

  P and T are pressure and temperature

  1 and 2 are initial and final values

        \frac{0.25}{273}   = \frac{P2}{398}  

         P2  = 0.37atm

3 0
2 years ago
Copper is an example of a(n)
expeople1 [14]

copper is not a stone, copper is not a consumption resource, and copper is not renewable, that means that :

d. nonrenewable resource

Explanation:

A nonrenewable source is a source of economic value that cannot be immediately displaced by natural means on a level equal to its destruction. Most fossil fuels, such as oil, natural gas, and coal are estimated nonrenewable resources in that their use is not sustainable because their production takes billions of years.

7 0
3 years ago
Read 2 more answers
What is the mass of volume= 5.4 mL  density= 2.5 g/mL​
ddd [48]

Answer:

13.5g

Explanation:

Mass is defined as the measure of the amount of matter in an object. Its unit is kg or g.

Mass can be calculated using the formula:

m= d × v

where,

d= density

m= mass

v= volume

m= 2.5×5.4

m= 13.5g

5 0
3 years ago
In solid NaCl, the equilibrium separation between neighboring Na+ and Cl- ions is 0.283 nm. Calculate the coulombic energy betwe
const2013 [10]

Explanation:

It is given that r = 0.283 nm. As 1 nm = 10^{-9} m.

Hence, 0.283 nm = 0.283 \times 10^{-9} m

  • Formula for coulombic energy is as follows.

             U_{coulomb} = -1.748 \frac{e^{2}}{4 \pi \epsilon_{o} r}

where,   e = 1.6 \times 10^{-19} C

            \epsilon_{o} = 8.85 \times 10^{-12}

          U_{coulomb} = -1.748 \frac{(1.6 \times 10^{-19}^{2}}{4 \times 3.14 \times 8.85 \times 10^{-12} \times 0.283 \times 10^{-9}}

                         = 1.423 \times 10^{-18} J

  • As 1 eV = 1.6 \times 10^{-19} J

So,       1 J = \frac{1 eV}{1.6 \times 10^{-19}}

Hence,    U = \frac{1.423 \times 10^{-18} J}{1.6 \times 10^{-19} J}

                   = 8.9 eV

  • Also,   1 J = \frac{10^{-3} kJ}{6.022 \times 10^{23}mol}

                = 1.67 \times 10^{-27} kJ/mol

Therefore, U = 1.423 \times 10^{-18} J \times 1.67 \times 10^{-27} kJ/mol

                     = 2.37 \times 10^{-45} kJ/mol

7 0
3 years ago
The main criterion for sigma bond formation is that the two bonded atoms have valence orbitals with lobes that point directly at
nalin [4]

Answer:

The given statement - The main criterion for sigma bond formation is that the two bonded atoms have valence orbitals with lobes that point directly at each other along the line between the two nuclei , is <u>True.</u>

Explanation:

The above statement is correct , because the sigma bond is produced by the head on overlapping, the orbitals should all point in the same direction.

<u>SIGMA BONDS -</u> Sigma bonds (bonds) are the strongest type of covalent chemical bond in chemistry. They're made up of atomic orbitals that collide head-on. For diatomic molecules, sigma bonding is best characterized using the language and tools of symmetry groups.

Head-on overlapping of atomic orbitals produces sigma bonds. The concept of sigma bonding is expanded to include bonding interactions where a single lobe of one orbital overlaps with a single lobe of another. Propane, for example, is made up of ten sigma bonds, one for each of the two CC bonds and one for each of the eight CH bonds.

Hence , the answer is true .

6 0
3 years ago
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