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3 years ago

What is the electron configuration of an element with atomic number 20?

Chemistry

2 answers:

Vedmedyk [2.9K]3 years ago

8 0

[Ar]4s^2
hope it helps

blagie [28]3 years ago

4 0

Answer:

What is the electron configuration of an element with atomic number 20? 1s2 2s2 2p6 3s2 3p6 4s2

Explanation:

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Which substance is a base? HCOOH RbOH H2CO3 NaNO3

Alex Ar [27]

Answer:

RbOH

Explanation:

For this question, we have to remember what is the definition of a base. A base is a compound that has the ability to produce hydroxyl ions $OH^-$ , so:

$AOH~->~A^+~+~OH^-$

With this in mind we can write the reaction for each substance:

$HCOOH~->~HCOO^-~+~H^+$

$RbOH~->~Rb^+~+~OH^-$

$H_2CO_3~->~CO_3^-^2~+~2H^+$

$NaNO_3~->~Na^+~+~NO_3^-$

The only compound that fits with the definition is $RbOH$ , so this is our base.

I hope it helps!

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3 years ago

Read 2 more answers

Why is it important for scientists to review and repeat the work of other scientists?

Veronika [31]

Scientists repeat experiments for reliability. Experiments have to be repeated, since performing an experiment only once, does not prove a scientists theory on the experiment, which they develop by performing the experiment. And then performing the experiment again or even many times to prove or disapprove their theories. Btw, before an experiment begins, the scientist will make a hypothesis of what they believe will happen. If proven correctly, they would then use those results they record throughout the experiment, from beginning to end to prove whether or not their hypothesis are correct or incorrect. Click to let others know, how helpful is it

Read more on Brainly.com - brainly.com/question/2613050#readmore

So that they can prove the other scientists views wrong and develop a new theory in which there is more sense and credibility.

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BASICALLY, I THINK THE ANSWER IS 1 OR 2 OR

7 0

3 years ago

Read 2 more answers

Find the enthalpy of neutralization of HCl and NaOH. 137 cm3 of 2.6 mol dm-3 hydrochloric acid was neutralized by 137 cm3 of 2.6

liraira [26]

Answer : The correct option is, (D) 89.39 KJ/mole

Explanation :

First we have to calculate the moles of HCl and NaOH.

$\text{Moles of HCl}=\text{Concentration of HCl}\times \text{Volume of solution}=2.6mole/L\times 0.137L=0.3562mole$

$\text{Moles of NaOH}=\text{Concentration of NaOH}\times \text{Volume of solution}=2.6mole/L\times 0.137L=0.3562mole$

The balanced chemical reaction will be,

$HCl+NaOH\rightarrow NaCl+H_2O$

From the balanced reaction we conclude that,

As, 1 mole of HCl neutralizes by 1 mole of NaOH

So, 0.3562 mole of HCl neutralizes by 0.3562 mole of NaOH

Thus, the number of neutralized moles = 0.3562 mole

Now we have to calculate the mass of water.

As we know that the density of water is 1 g/ml. So, the mass of water will be:

The volume of water = $137ml+137ml=274ml$

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/ml\times 274ml=274g$

Now we have to calculate the heat absorbed during the reaction.

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = heat absorbed = ?

$c$ = specific heat of water = $4.18J/g^oC$

m = mass of water = 274 g

$T_{final}$ = final temperature of water = 325.8 K

$T_{initial}$ = initial temperature of metal = 298 K

Now put all the given values in the above formula, we get:

$q=274g\times 4.18J/g^oC\times (325.8-298)K$

$q=31839.896J=31.84KJ$

Thus, the heat released during the neutralization = -31.84 KJ

Now we have to calculate the enthalpy of neutralization.

$\Delta H=\frac{q}{n}$

where,

$\Delta H$ = enthalpy of neutralization = ?

q = heat released = -31.84 KJ

n = number of moles used in neutralization = 0.3562 mole

$\Delta H=\frac{-31.84KJ}{0.3562mole}=-89.39KJ/mole$

The negative sign indicate the heat released during the reaction.

Therefore, the enthalpy of neutralization is, 89.39 KJ/mole

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How long is a red blood cell

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3 years ago

What is the lewis dot structure for AgBr? PLS HELP ME

Alinara [238K]

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