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3 years ago

The closest star to our Sun is Proxima

Chemistry

1 answer:

vichka [17]3 years ago

6 0

Answer:

Distance in kilometre = 4.242 x 10¹² km

Explanation:

Given:

Distance of Proxima Centauri = 4.242 light years

Find:

Distance in kilometre

Computation:

1 light year = 10,000,000,000,000 km

So,

4.242 light years = 4.242 x 10,000,000,000,000

Distance in kilometre = 4.242 x 10¹² km

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How many valence electrons does oxygen have?<br> A. 2<br> B. 6<br> C. 8<br> D. 16

AleksandrR [38]

Oxygen has 6 valence electrons, so B

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3 years ago

Consider the following balanced thermochemical equation for a reaction sometimes used for H2S production:

fgiga [73]

Answer:

d. Heat is released from the reaction

Explanation:

A negative enthalpy change indicates that it is an exothermic reaction. Exothermic reactions release heat.

5 0

3 years ago

Points

ExtremeBDS [4]

The answer is D. A compound

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3 years ago

How many moles are present in

olasank [31]

Answer: (a) There are 0.428 moles present in 12 g of $N_{2}$ molecule.

(b) There are 2 moles present in $12.044 \times 10^{23}$ particles of oxygen.

Explanation:

(a). The mass of nitrogen molecule is given as 12 g.

As the molar mass of $N_{2}$ is 28 g/mol so its number of moles are calculated as follows.

$No. of moles = \frac{mass}{molar mass}\\= \frac{12 g}{28 g/mol}\\= 0.428 mol$

So, there are 0.428 moles present in 12 g of $N_{2}$ molecule.

(b). According to the mole concept, 1 mole of every substance contains $6.022 \times 10^{23}$ atoms.

Therefore, moles present in $12.044 \times 10^{23}$ particles are calculated as follows.

$Moles = \frac{12.044 \times 10^{23}}{6.022 \times 10^{23}}\\= 2 mol$

So, there are 2 moles present in $12.044 \times 10^{23}$ particles of oxygen.

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3 years ago

Using hooke's law , f s p r i n g = k ^ x , find the force needed to strech a spring 2 cm if it has an elastic constant of 3 N/c

dlinn [17]

I believe it is D. 6 N

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3 years ago