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4 years ago

The half-life of bismuth is 5 days. How much of a 100 gram sample will remain after 20 days?

1 answer:

8 0

Half-life is the duration needed for a compound to decay into half of its initial weight. In this case, the initial weight is 100gram. The calculation for the final weight should be:

final weight= initial weight * (1/2)^(duration/half-life)
final weight= 100 grams * (1/2)^(20days/5 days)
final weight= 100 grams * (1/2)^(4)
final weight= 100 * 1/16= 100/16 gram= 6.25 grams

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What pressure, in atmospheres, is exerted on the body of a diver if he is 38 ft below the surface of the water when atmospheric

Talja [164]

The pressure of diver = atmospheric pressure + water pressure

atmospheric pressure = 750 mmHg (as given) = 750 / 760 atm = 0.987 atm

Water pressure is

P = hρg

where

h = height of water = 38 ft

1 ft = 0.3048

38 ft = 11.58 m

ρ = density = 1000 Kg / m³

g = gravitational constant = 9.81 m/s2

P = 11.58 X 1000 X 9.81 = 113599.8 Kg / m s^2 Or N /m^2

1 N / m^2 = 1 pa = 9.869 X 10^-6 atm

P = 113599.8 Pa = 1.12 atm

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4 years ago

There are 0.55 moles of carbon dioxide gas in a 15.0 L container. This container is at a temperature of 300 K. What is the press

sertanlavr [38]

Answer:

$\large \boxed{\text{D.) 91 kPa}}$

Explanation:

We can use the Ideal Gas Law — pV = nRT

Data:

V = 15.0 L

n = 0.55 mol

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Calculation:

$\begin{array}{rcl}pV & =& nRT\\p \times \text{15.0 L} & = & \text{0.55 mol} \times \text{8.31 kPa$\cdot$ L$\cdot$K$^{-1}$mol$^{-1}\times$ 300 K}\\15.0p & = & \text{1370 kPa}\\p & = & \textbf{91 kPa}\end{array}\\\text{The pressure in the container is $\large \boxed{\textbf{91 kPa}}$}$

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3 years ago

A student touches a freshly baked cake that was taken out of the oven. Which best explains why the cake feels hot? Options: Mole

chubhunter [2.5K]

Answer:

Molecules in the cake are moving faster than molecules in the skin.

Explanation:

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Anna71 [15]

Answer:

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Lelechka [254]

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4 years ago

Read 2 more answers