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3 years ago

6

Which of the following elements is commonly found in the Earth's crust, living matter, oceans, and atmosphere? hydrogen , neon g

old or bromine?

1 answer:

Svetlanka [38]3 years ago

4 0

Answer: hydrogen

Explanation: hydrogen gas is a major component of water which occupies a large portion of the Earth's atmosphere

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Each period in the periodic table corresponds to an energy sublevel or the principle energy level?

ELEN [110]

Each period in the periodic table corresponds to a principal energy level

6 0

3 years ago

If element X has 83 protons, how many electrons does it have? ______ electrons

Zolol [24]

The element has 83 electrons

5 0

3 years ago

Thorium-234 has a half-life of 24.1 days. How many grams of a 150 g sample would you have after 120.5 days?

chubhunter [2.5K]

Answer:

8.625 grams of a 150 g sample of Thorium-234 would be left after 120.5 days

Explanation:

The nuclear half life represents the time taken for the initial amount of sample to reduce into half of its mass.

We have given that the half life of thorium-234 is 24.1 days. Then it takes 24.1 days for a Thorium-234 sample to reduced to half of its initial amount.

Initial amount of Thorium-234 available as per the question is 150 grams

So now we start with 150 grams of Thorium-234

$150 \times \frac{1}{2}=24.1$

$75 \times \frac{1}{2} =48.2$

$34.5 \times \frac{1}{2} =72.3$

$17.25 \times \frac{1}{2} =96.4$

$8.625\times \frac{1}{2} =120.5$

So after 120.5 days the amount of sample that remains is 8.625g

In simpler way , we can use the below formula to find the sample left

$A=A_{0} \cdot \frac{1}{2^{n}}$

Where

$A_0$ is the initial sample amount

n = the number of half-lives that pass in a given period of time.

7 0

3 years ago

C4H9OH(g)+O2(g)→CO2(g)+?H2O(l) what coefficient should be placed in front of H2O to balance the hydrogen atoms?

slava [35]

Answer:

5

Explanation:

To balance the hydrogen atoms, we check the number of hydrogen on the left side, this is equal to the 10 hydrogen atoms we have in the alkanol.

Now, on the right hand side, we can see we only have two hydrogen atoms in the water molecule. Now, to make equal the number of hydrogen atoms on both sides, we simply multiply the number of hydrogen there by 5 to make it 10 too

3 0

3 years ago

Which of the following best describes magnetic fields

BigorU [14]

Well the multiple choices for this question would be helpful, but from my own knowledge I would say:

Magnetic fields have north and south magnetic poles.

Magnetic fields have various characteristics which includes; they originate from the north poles and flow towards the south poles, they are exhibited in the form of magnetic field lines. Magnetic fields lines never cross one another,they all have the same strength and seek the path of least resistance between opposite magnetic poles etc.

3 0

3 years ago