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Lapatulllka [165]
3 years ago
5

Which element has 2 valence electrons and is in period 4?

Chemistry
1 answer:
KatRina [158]3 years ago
6 0
The correct answer is calcium. We know this because if we look at the periodic table calcium is the only option in period 4.
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What does the process of natural selection involve
Lorico [155]

Answer:

Only the organisms best adapted to their environment tend to survive and transmit their genetic characters in increasing numbers to succeeding generations while those less adapted tend to be eliminated.

Explanation:

According to Darwin's Theory of Evolution.

Hope this helped.

5 0
3 years ago
Which answer choice lists the number and type of elements in a compound in the way that is close to their actual arrangement?
alexandr1967 [171]

The chemical formula of a compound express the atoms by which the molecule is formed and the ratio of the atoms in which they are combined.

The space filling model of a compound describe the electron density in the compound of each atom.

The ball and stick arrangement of a compound describe the way in which the molecules are present in three dimensions.

The structural formula state the number of atoms present in the molecule, the type of element or atom present in the molecule and the way in which they are arranged closely which is the bond.

Thus only the structural formula only will cover all the options as stated.

6 0
3 years ago
5 Questions to answer please
ryzh [129]
1.Type of bonding in which electrons are completely transferred is called ionic bond.
2. Isotopes have same atomic number but different atomic mass number.
Atomic number = number of protons + number of neutrons
Therefore, A is correct. 
3. Nucleus is composed of neutrons and protons.
4. Chemical reactions follows the law of conservation of mass. Therefore mass of reactant = mass of product = 4 grams.
5. Again, mass of table salt formed should be equal to mass of (Na+Cl₂) = 4 grams.
5 0
3 years ago
Read 2 more answers
What is the density of an 800 gram object that occupies 200 cm 3 ?
vova2212 [387]
Density = mass/volume = 800/200 =4 g/cm^3
8 0
3 years ago
N⁻³ and Na⁺ have same<br> A Atomic no. <br>B Mass No. <br>C No. of electrons <br>D No. of neutrons​
gizmo_the_mogwai [7]

Answer:

C.) No. of electrons

Explanation:

A.) is incorrect. The atomic number represents the number of protons in an element. Nitrogen (N) and sodium (Na) always have a differing amount of protons.

B.) is incorrect. The mass number represents the number of protons and neutrons in an element. The number of neutrons and protons are specific to each element (disregarding isotopes). When elements ionize, these amounts are not altered.

C.) is correct. When an element becomes an ion, the number of electrons change. When nitrogen gains 3 electrons and sodium loses 1 electron, they end up having the same number of electrons (10).

D.) is incorrect. When elements ionize, the number of neutrons does not change. The only way two different elements could have the same number of neutrons is if at least one of the elements is an isotope. Isotopes are two or more atoms of the same element that differ in their amounts of neutrons.

3 0
2 years ago
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