Answer:
a. PbO.
Explanation:
- The formula unit of a stable chemical compound should maintain that the overall charge of the compound is zero <em>(not charged)</em>.
- The formula unit of a compound is represented by the lowest ratio numbers of the ions forming the compound.
<em>Choice a:</em> is the right answer PbO
- That lead is divalent cation Pb²⁺ and O is considered as a divalent anion O²⁻.
- So, the formula unit contains Pb:O with a ratio of 1:1 (PbO)
<em>Choice b: </em>is a wrong choice Li₂B
- The lithium cation is a monovalent cation Li¹⁺ and boron is a trivalent cation B³⁺, so we can not do that.
<em>Choice c:</em> is a wrong choice Al₂Pb₃
- that Al is a trivalent cation Al³⁺ and Pb is a divalent cation Pb²⁺, so we can not do this for the two cations.
<em>Choice d:</em> is a wrong choice ClO
- that Cl may act as Cl¹⁺ and O acts as O²⁻, so the right formula unit should be Cl₂O.
Answer:
Spina bifida is a condition that affects the spine and is usually apparent at birth. It is a type of Neural Tube Defect (NTD).
Answer:
Explanation:
In gases the particles move rapidly in all directions, frequently colliding with each other and the side of the container. With an increase in temperature, the particles gain kinetic energy and move faster. ... In liquids, particles are quite close together and move with random motion throughout the container.
PH + pOH = 14
pH = 14 - pOH = 14 - 2 = 12
A pOH of 2 is equivalent to a pH of 12. A pH greater than 7 is basic, and 12 is greater than 7. Therefore, a solution with a pOH of 2 is basic.
Thus, the correct answer choice is B.
So there are three formulas that you must be aware of hen attempting these questions (by technicality, only two because the third is a transposition of the second).
These formulas are :
mole x L = # of atoms (where L = Avogadro's Constant)
mass / Mr = mole (where Mr = Molar Mass)
Mole x Mr = mass
So no we can easily ace these questions
1) a. 98.3 g of Hg
mass of Hg = 98.3g
Mr " " = 201 g / mol
mole =
= 0.489 mol
∴ # of atoms = 0.489 mol * (6.03 * 10²³)
= 2.95 * 10²³ atoms
c. 10.7g of Li
mass of Li = 10.7 g
Mr " " = 7 g / mol
thus mole =
= 1.529 mol
# of atoms = 1.529 mol * (6.03 * 10²³)
= 9.22 * 10²³
2) a. 6.84 g of C₁₂H₂₂O₁₁
mass of sucrose = 6.84 g
Mr " " = ∑ (Mr of each element * amount of each element's atom)
= ∑ [(12 * 12)+(1 * 12)+(16 * 11)] g / mol
= 342 g / mol
∴ mole of sucrose =
= 0.02 mol
c) 68.0g of NH<span>₃</span>
<span> mass of NH₃ = 68.0 g</span>
<span> Mr " " = [(14 * 1) + ( 1 * 3)] g / mol</span>
<span> ∴ mole of NH₃ = </span>
= 4 mol
3) a. 3.52 mol of Si
mole of Si = 3.52 mol
Mr " " = 28 g / mol
Mass = 3.52 mol * 28 g / mol
= 98.56 g
c. 0.550 mol of F₂
mol of F₂ = 0.55 mol
Mr " " = (19 * 2 ) g / mol
Mass = 0.55 mol * 38 g / mol
= 20.9 g
Hope I as clear in my answers and that they helped