Answer:
The correct answer is 4
Explanation:
Boron trifluoride (BF₃) has a molecular geometry (as shown in the image in the question) referred to as trigonal planar; this is because each of the the fluorine atoms/molecules (bonded to the central boron atom) is placed in such a way that they form the three "end points"/"domains" of an equilateral triangle. Hence, the correct option is the last option.
C most likely sorry if I’m wrong
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Answer: The volume occupied by 2.50 moles of
gas at STP is 56.0L
Explanation:
According to ideal gas equation:

P = pressure of gas = 1 atm (at STP)
V = Volume of gas = ?
n = number of moles = 2.50
R = gas constant =
T =temperature =
(at STP)


Thus the volume occupied by 2.50 moles of
gas at STP is 56.0L
Answer:
Calcium
Explanation:
The symbol for the element with a mass number of 27 is actually Al for Aluminum instead of Co for Cobalt. Mass number refers to atomic mass, not atomic number.
Aluminum has an atomic mass of 26.982 or 27.
The letters to unscramble are I, M, C, Al, U, and C.
The mystery element is Calcium.
Hope that helps.