BeH2 has no lone pairs of electrons. What's the structure of this molecule?

Iron-56, Iron-54, and Iron-58 are all ____ of iron

JulijaS [17]

Answer:

in the 50 place

Explanation:

3 0

4 years ago

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PLZ HELP ...The half-life of polonium-218 is 3.0 minutes. If you start with 40.0 g, how long will it be before only 4.5 g remain

Elanso [62]

Answer:- 9.4 minutes.

Solution:- Radioactive decay obeys first order reaction kinetics and the equation used to solve this type of problems is:

$lnN=-kt+lnN_0$

where, k is decay constant and t is the time. $N_0$ is the initial amount of the radioactive substance and N is the remaining amount.

Since the value of decay constant is not given, so we need to calculate it first from given half life by using the formula:

$k=\frac{0.693}{t_1_/_2}$

where $t_1_/_2$ stands for half life.

Given half life is 3.0 minutes.

So, $k=\frac{0.693}{3.0min}$

$k=0.231min^-^1$

Let's plug in the values in the first order reaction equation and solve it for t.

$ln4.5g=-0.231min^-^1(t)+ln40.0g$

It could also be written as:

$ln(\frac{4.5g}{40.0g})=-0.231min^-^1}$

$-2.18=-0.231min^-^1}$

$t=\frac{-2.18}{-0.231min^-^1}$

k = 9.4 min

So, the radioactive substance would take 9.4 minutes to decay from 40.0 grams to 4.5 grams.

4 0

3 years ago

Calculate the vapor pressure of spherical water droplets of radius (a) 17 nm and (b) 2.0 μm surrounded by water vapor at 298 K.

Montano1993 [528]

Explanation:

Relation between pressure of water and its droplet is as follows.

$ln (\frac{p}{p_{o}}) = \frac{2 \gamma M}{r \rho RT}$

where, p = pressure of droplet

$p_{o}$ = water pressure in given temperature

$\gamma$ = $7.99 \times 10^{-3}$

M = Molecular Weight in Kg/Mol (0.018 for water)

r = radius in meters

$\rho$ = density of water in $Kg/m^{3}$ (1000 $kg/m^{3}$ )

R = ideal gas constant (8.31)

T = temperature in Kelvin

(a) We will calculate the value of p as follows.

p = $e^{\frac{2 \gamma M}{r \rho RT}} \times p_{o}$

= $e^{\frac{2 \times 0.07199 \times 0.018}{1.7 \times 10^{-8} \times 1000 \times 8.31 \times 298 K} \times 25.2$

= 26.8 torr

(b) And, vapor pressure of spherical water droplets of radius 2.0 $\mu m$ or $2 \times 10^{-6} m$

p = $e^{\frac{2 \gamma M}{r \rho RT}} \times p_{o}$

= $e^{\frac{2 \times 0.07199 \times 0.018}{2 \times 10^{-6} \times 1000 \times 8.31 \times 298 K} \times 25.2$

= 25.2 torr

7 0

4 years ago

PLEASE HELP!!!

Kaylis [27]

I think it comes from Fungi. I'm not 100% sure about that though.

8 0

3 years ago

Write out the word equations for these reactions.<br> ) Hydrogen reacts with oxygen to form water.

ale4655 [162]

Answer:

H2O

Explanation:

PLS MARK ME TO THE BRAINLIST

4 0

3 years ago