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3 years ago

Why are polar bears listed as a threatened species?

2 answers:

8 0

Because of global warming, as our ozone layer gets disrupted the ice caps are melting and the polar bear have no where to go

IceJOKER [234]3 years ago

5 0

Because their species is in danger of going extinct<span />

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How many moles of helium are 8.84×10^24 atoms of He?

viva [34]

Answer:

14.77 mol.

Explanation:

It is known that every 1.0 mole of compound or element contains Avogadro's number (6.022 x 10²³) of molecules or atoms.

<u><em>Using cross multiplication:</em></u>

1.0 mole of He contains → 6.022 x 10²³ atoms.

??? mole of He contains → 8.84 x 10²⁴ atoms.

<em>∴ The no. of moles of He contains (8.84 x 10²⁴ atoms) </em>= (1.0 mol)(8.84 x 10²⁴ atoms)/(6.022 x 10²³ atoms) =<em> 14.77 mol.</em>

8 0

3 years ago

Question 6 (4 points)

pishuonlain [190]

Answer:

20.9%

Explanation:

I took the test i hope this helps:)

8 0

3 years ago

Read 2 more answers

In a sample containing 100 atoms of X, 70 were found to be 9X while 30 were 11X isotopes. Determine the average relative atomic

Burka [1]

The average relative atomic mass of a sample containing 100 atoms of X, 70 were found to be 9X while 30 were 11X isotopes is 9.6g.

<h3>What is Atomic mass? </h3>

Atomic mass is defined as the whole mass of an atom.

It is also defined as the sum of atomic number and number of neutrons.

Atomic mass = Atomic number + neutrons

<h3>What is Isotopes?</h3>

Isotopes are the those element which have same atomic number but have different mass number and number of neutrons.

The average relative atomic mass can be calculated as

mass of isotopes/ mass of sample

mass of all isotopes = (70 × 9X) + (30 × 11X)

=(630 + 330) X

= 960X

Average relative atomic mass = 960X/ 100 X

= 9.6 g

Thus, we concluded that the average relative atomic mass of a sample containing 100 atoms of X, 70 were found to be 9X while 30 were 11X isotopes is 9.6g.

learn more about atomic mass:

brainly.com/question/14250653

#SPJ9

5 0

1 year ago

Consider the nuclear equation below. Superscript 235 subscript 92 upper U right arrow superscript 4 subscript 2 upper H e. What

coldgirl [10]

Answer:

$\rm_{90}^{231}\text{Th}$

Explanation:

The unbalanced nuclear equation is

$\rm _{92}^{235}\text{U} \longrightarrow \, _{2}^{4}\text{He} + X$

Let's write X as a nuclear symbol.

$\rm _{92}^{235}\text{U} \longrightarrow \, _{2}^{4}\text{He} + _{Z}^{A}\text{X}$

The main point to remember in balancing nuclear equations is that the sums of the superscripts and of the subscripts must be the same on each side of the reaction arrow.

Then

235 = 4 + A , so A = 235 - 4 = 231, and

92 = 2 + Z , so Z = 92 - 2 = 90

And your nuclear equation becomes

$\rm _{92}^{235}\text{U} \longrightarrow \, _{2}^{4}\text{He} +\, _{90}^{231}\text{X}$

Element 90 is thorium, so

$\rm X = _{90}^{231}\text{Th}$

7 0

3 years ago

How many moles of aluminum metal are required to produce 4.04 L of hydrogen gas at 1.11 atm and 27 °C by reaction with HCl?

Strike441 [17]

Answer:

0.121 moles of aluminum metal are required to produce 4.04 L of hydrogen gas at 1.11 atm and 27 °C by reaction with HCl

Explanation:

This is the reaction:

2 Al(s) + 6 HCl(aq) → 2 AlCl₃ (aq) + 3 H₂(g)

To make 3 moles of H₂, we need 2 moles of Al.

By conditions given, we will find out how many moles of H₂ do we have.

Let's use the Ideal Gas Law

P. V = n . R . T

1.11 atm . 4.04L = n . 0.082 L.atm/mol.K . 300K

(1.11 atm . 4.04L) / (0.082 mol.K/L.atm . 300K) = n

0.182 mol = n

So the rule of three will be:

If 3 moles of H₂ came from 2 moles of Al

0.182 moles of H₂ will come from x

(0.182 .2) / 3 = 0.121 moles

4 0

4 years ago