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3 years ago

12

Sodium (Na) and potassium (K) are in the same group in the periodic table. Sodium is in the 11th position. How many valence elec

trons does potassium have?
0

1

9

11

2 answers:

lapo4ka [179]3 years ago

8 0

It's 1 because there is only one electron on the outer shell.

Studentka2010 [4]3 years ago

5 0

Answer: Option (b) is the correct answer.

Explanation:

As it is known that both sodium and potassium are same group elements. Both of then belongs to group 1A.

Since, sodium is at 11th position in the periodic table and its atomic number is also 11. Therefore, electronic distribution of sodium is 2, 8, 1.

Similarly, potassium is placed at 19th position in the periodic table and its atomic number is 19. So, electronic distribution of potassium is 2, 8, 8, 1.

It is known that valence electrons are the electrons present in the outermost shell of an atom.

So, in a potassium atom there is only one valence electron is present.

Thus, we can conclude that potassium have 1 valence electron.

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shepuryov [24]

Answer:

The mass of solid with density 14.2 g/cm3 and volume 350 cm3 is 4.97 Kg.

Explanation:

Formula for density is given below :

$density = \frac{mass}{volume}$

$volume = 350 cm^{3}$

$density = 14.2 g/cm^{3}$

Insert the values in the formula

$14.2 = \frac{mass}{350}$

on cross multiplication :

$mass = density\times volume$

$mass = 14.2\times 350$

$mass = 4970 g$

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$mass =4970\times 0.001 Kg$

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Note : Check the units of volume and density carefully

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3 years ago

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Nat2105 [25]

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2 years ago

If 45.0 mL of ethanol (density = 0.789 g/mL) initially at 8.0 ∘C is mixed with 45.0 mL of water (density = 1.0 g/mL) initially a

strojnjashka [21]

Answer : The final temperature of the mixture is, $22.14^oC$

Explanation :

First we have to calculate the mass of ethanol and water.

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and,

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Now we have to calculate the final temperature of the mixture.

In this problem we assumed that heat given by the hot body is equal to the heat taken by the cold body.

$q_1=-q_2$

$m_1\times c_1\times (T_f-T_1)=-m_2\times c_2\times (T_f-T_2)$

where,

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$c_2$ = specific heat of water = $4.18J/g^oC$

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$m_2$ = mass of water = 45.0 g

$T_f$ = final temperature of mixture = ?

$T_1$ = initial temperature of ethanol = $8.0^oC$

$T_2$ = initial temperature of water = $28.6^oC$

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

$35.5g\times 2.42J/g^oC\times (T_f-8.0)^oC=-45.0g\times 4.18J/g^oC\times (T_f-28.6)^oC$

$T_f=22.14^oC$

Therefore, the final temperature of the mixture is, $22.14^oC$

3 0

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kogti [31]

i think it is this

Explanation:

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nadezda [96]

Answer:

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6 0

2 years ago

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