Answer : The correct option is, (D) CO₂, BCl₃, and Fe³⁺
Explanation :
According to the Lewis concept, an acid is defined as a substance that accepts electron pairs and base is defined as a substance which donates electron pairs.
(a) 
It is a Lewis-acid because it can accepts electron pairs.
(b) 
It is not a Lewis-acid because it can not accepts electron pairs but it is a base because it can donates and accept hydrogen ion.
(c) 
It is a Lewis-acid because it can accepts electron pairs because it has an incomplete octet and an empty 2p orbital.
(d) 
It is a Lewis-acid because it can accepts electron pairs.
Hence, the ions which behave as Lewis acids are, CO₂, BCl₃, and Fe³⁺
Answer:
Lithium
Explanation:
Lithium is an alkali metal. This means that lithium is expected to be a member of the group one elements on the periodic table.
The group one elements ionize by losing one electron. Hence, the form univalent positive ions after ionization.
Lithium has 3 electrons, 2 belonging to the k shell with the valence L having the other electron. Upon ionization, it forms the ion Li+.
This means it has lost the electron in the valence shell probably through an ionic transfer. This means the only electron it has is in the S shell, which is of a smaller size when compared to elements having multiple rings of shell.
It is expected that negative ions become larger when they ionize as they receive more electrons while that of metals I.e positive electrons shrink when they ionize as they are givers of electrons.
Stoichiometry:
First, calculate the number of grams for one mole of Ca3 (PO3)4
(3 * (Mass of Ca)) + (4 * (Mass of P + (3 * Mass of Oxygen)))
= (3*40.08) + 4(30.97 + (3*16.00))
=(120.24) + 4(78.97)
=436.12 g / mol Ca3(PO3)4
This means there are 436.12 g per 1 mole of Ca(PO3)4. Since there are 4.50 moles of Calcium Phosphate, mulitply the molar mass of Ca(PO3)4 by 4.50 and you should get 1962.54 g. Since there are 3 sigfigs, the final answer is 1960 g.
on a side note: I put in all my work in case 1. your periodic table if different, 2. my work is wrong, 3. you put in the question wrong because I feel that the actual compound would be Ca3(PO4)3 instead of Ca3(PO3)4 (if this is the case, the answer should be 1820 g).
Atomic radius decreases across a period because valence electrons are being added to the same energy level at the same time the nucleus is increasing in protons. The increase in nuclear charge attracts the electrons more strongly, pulling them closer to the nucleus.
Answer: No hydrogen bond cannot occur in this alpha helix structure.
Explanation: For hydrogen bond to form, the electronegativity difference should be more than 1.7. carbon has an electronegativity of 2.5 whereas hydrogen has 2.1 so their electronegativity difference is 0.3. So in this alpha helix structure cannot occur.
