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3 years ago

6

Based on the models, why do you think helium is number 2( the second element) and beryllium number 4( the fourth element) on the

periodic table?

1 answer:

Andrei [34K]3 years ago

8 0

The atomic number here refers to the number of electron that the atom has. helium only has 2 electrons and beryllium has 4 electron

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6. What volume would be occupied by 7.75 g of this same substance?

Kaylis [27]

D = m/V
<span>V = m/d
V= 7.75 g / 1.71 g/cm^3
V= 4.53 c</span>m^3

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4 years ago

Liquid sodium is being considered as an engine coolant. How many grams of liquid sodium (minimum) are needed to absorb 1.20 MJ 1

mars1129 [50]

Answer : The mass of liquid sodium needed are, $3.17\times 10^3g$

Explanation :

First we have to calculate the number of moles of liquid sodium.

$q=n\times c\times (\Delta T)$

where,

q = heat absorb = 1.20 MJ = 1.20 × 10⁶ J

n = number of moles of liquid sodium = ?

c = specific heat capacity = $30.8J/mol.K$

$\Delta T$ = change in temperature = $10.0^oC=273+10.0=283K$

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

$1.20\times 10^6J=n\times 30.8J/mol.K\times 283K$

$n=137.7mol$

Now we have to calculate the mass of liquid sodium.

Molar mass of Na = 23 g/mol

$\text{Mass of Na}=\text{Moles of Na}\times \text{Molar mass of Na}$

$\text{Mass of Na}=137.7mol\times 23g/mol=3167.1g=3.17\times 10^3g$

Therefore, the mass of liquid sodium needed are, $3.17\times 10^3g$

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4 years ago

Which ion was formed by providing the second ionization energy to remove an electron?

DerKrebs [107]

If we remove 2 electrons, the new charge will be positive by 2 units. Hence, the ion is $Ca^{2+}$ .

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3 years ago

Which of the following is the best example of a "Scientific Question"?

Tju [1.3M]

Answer:

B

Explanation:

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