All categories

4 years ago

Select the correct statement below:

Chemistry

1 answer:

uranmaximum [27]4 years ago

5 0

Answer: The correct answer is Option D.

Explanation:

Valence electrons are defined as the electrons which are present in the outermost shell of the atom. Outermost shell has the highest value of 'n' that is principal quantum number.

For the given options:

Option A:

Phosphorus is the 15th element of the periodic table having electronic configuration $1s^22s^22p^63s^23p^3$

Number of valence electrons = 2 + 3 = 5

The '3s' orbital is fully filled and all the three '3p' orbitals are half filled for the given element.

So, the given statement is not correct.

Option B:

Aluminium is the 13th element of the periodic table having electronic configuration $1s^22s^22p^63s^23p^1$

Number of valence electrons = 2 + 1 = 3

The '3s' orbital is fully filled and one of all the three '3p' orbitals is half filled and rest are empty for the given element.

So, the given statement is not correct.

Option C:

Calcium is the 20th element of the periodic table having electronic configuration $1s^22s^22p^63s^23p^64s^2$

Number of valence electrons = 2

The '4s' orbital is fully filled and all the three '4p' orbitals are half filled for the given element. '4s' sub-shell has only one orbital.

So, the given statement is not correct.

Option D:

Sodium is the 11th element of the periodic table having electronic configuration $1s^22s^22p^63s^1$

Number of valence electrons = 1

The '3s' orbital is half filled and all the three '3p' orbitals are half filled for the given element.

So, the given statement is not correct.

Hence, the correct answer is Option D.

You might be interested in

The activation energy for proline isomerization of a peptide depends on the identity of the preceding residue and obeys Arrheniu

MAVERICK [17]

Answer:

Activation energy of phenylalanine-proline peptide is 66 kJ/mol.

Explanation:

According to Arrhenius equation- $k=Ae^{\frac{-E_{a}}{RT}}$ , where k is rate constant, A is pre-exponential factor, $E_{a}$ is activation energy, R is gas constant and T is temperature in kelvin scale.

As A is identical for both peptide therefore-

$\frac{k_{ala-pro}}{k_{phe-pro}}=e^\frac{[E_{a}^{phe-pro}-E_{a}^{ala-pro}]}{RT}$

Here $\frac{k_{ala-pro}}{k_{phe-pro}}=\frac{0.05}{0.005}$ , T = 298 K , R = 8.314 J/(mol.K) and $E_{a}^{ala-pro}=60kJ/mol$

So, $\frac{0.05}{0.005}=e^{\frac{[E_{a}^{phe-pro}-(60000J/mol)]}{8.314J.mol^{-1}.K^{-1}\times 298K}}$

$\Rightarrow$ $E_{a}^{phe-pro}=65705J/mol=66kJ/mol$ (rounded off to two significant digit)

So, activation energy of phenylalanine-proline peptide is 66 kJ/mol

7 0

3 years ago

How many protons and electrons do the following ion have?

GalinKa [24]

a) Number of protons = number of electron in the atom = atomic number

So it has 7 protons answer

N-3 has gained 3 electron so number of electrons + 7+3

= 10 answer

8 0

4 years ago

H. Identity of unknown metal

OLEGan [10]

Answer:

you can identify an unknown substance by measuring its density and comparing your results to a list of known densities. Density=mass/volume. Assume that you have to identify an unknown metal. You can determine the mass of the metal on a scale.

8 0

4 years ago

HELP.....From the information presented in the activity series of metals below (4 metals included), answer the following questio

san4es73 [151]

Answer:

a)there would be no reaction

Explanation:

The activity series of metals has many functions. The one applicable to this problem is that it can be used to determine whether a reaction will occur or not. Also, based on the positions of metals in the series, we can know how reactive a metal is compared to another.

In a single displacement reaction, a metal replaces another metal based on their position on the activity series. Metals that are higher in the series are generally more reactive than others below them and so will displace them.

Would aluminum replace magnesium to form a new compound or would there be no reaction?

Magnesium is higher than aluminum in the activity series. Therefore it is more reactive than aluminum. No reaction will occur.

6 0

3 years ago

Atomic mass protons column electrons atomic number neutrons row 11 12 23

zysi [14]

A) Mass Number B) Protons and Electrons C) (I think group but I'm not 100% sure on this...) D) 12 (To work out the number of neutrons you do MASS number - ATOMIC number aka the number of protons so in this case you'd do 23-11=12) Hope this helps

3 0

4 years ago