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3 years ago

Where did the atoms come from in the first place?

Chemistry

2 answers:

Salsk061 [2.6K]3 years ago

4 0

Answer:

All the carbon atoms in the human body were created in the stars. Elementary particles, such as protons, were formed during the "big bang"; that amazing moment about 14 billion years ago in which the universe got it's start.

goldenfox [79]3 years ago

3 0

Answer:

Cheese

Explanation:

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The atomic number of magnesium (mg) is 12. this is also the number of which of the following

Rzqust [24]

The answer is protons.

8 0

3 years ago

A drag racing vehicle travels from 0 to 100 mph in 5 seconds north.what is the acceleration

arsen [322]

100mph = 100m/h

= 100m/h * 1 h/3600sec

= 0.028m/sec

= 0.028m/sec /5sec

= 0.055m/sec^2

6 0

4 years ago

Which of the following items is NOT a compound?

Ede4ka [16]

NaOH but you didnt give options

7 0

2 years ago

Determine the change in entropy for 2.7 moles of an ideal gas originally placed in a container with a volume of 4.0 L when the c

olchik [2.2K]

Answer:

The value of entropy change for the process $dS = 0.009 \frac{KJ}{K}$

Explanation:

Mass of the ideal gas = 0.0027 kilo mol

Initial volume $V_{1}$ = 4 L

Final volume $V_{2}$ = 6 L

Gas constant for this ideal gas ( R ) = $R_{u} M$

Where $R_{u}$ = Universal gas constant = 8.314 $\frac{KJ}{Kmol K}$

⇒ Gas constant R = 8.314 × 0.0027 = 0.0224 $\frac{KJ}{K}$

Entropy change at constant temperature is given by,

$dS = R log _{e} \frac{V_{2}}{V_{1}}$

Put all the values in above formula we get,

$dS = 0.0224 log _{e} [\frac{6}{4}]$

$dS = 0.009 \frac{KJ}{K}$

This is the value of entropy change for the process.

6 0

3 years ago

A chemist wishing to do an experiment requiring 47Ca2+(half-life = 4.536 days) needs 5.00 g of the nuclide. What mass of 47CaCO

Artyom0805 [142]

Answer: The answer is 6.78 grams.

Explanation: The equation used for solving this type of problems is:

$\frac{N}{N_0}=(\frac{1}{2})^n$

where, $N_0$ is the initial amount of radioactive substance, N is the remaining amount and n is the number of half lives.

Number of half lives is calculated on dividing the given time by the half life.

n = time/half life

Time is given as 48.0 hours and the half life is given as 4.536 days. let's make the units same and for this let's convert the half life from days to hours.

$4.536days(\frac{24hours}{1day})$

= 108.864 hours

So, $n=\frac{48.0}{108.864}$ = 0.441

Since 5.00 g is the required amount when the radioactive substance is delivered to the scientist, it would be the final amount that is N. We need to calculate the initial amount. Let's plug in the values in the equation:

$\frac{5.00}{N_0}=(\frac{1}{2})^0^.^4^4^1$

$\frac{5.00g}{N_0}=0.737$

$N_0=\frac{5.00g}{0.737}$

$N_0$ = 6.78 g

So, 6.78 g of the radioactive substance needs to be ordered.

4 0

4 years ago