Ageologist determines that a sample of a mineral can't be scratched by a steel nail but can be scratched by a masonry drill bit. based on this information, the sample mineral has to be softer than a. orthoclase. b. fluorite. c. apatite. d. corundum.

D. corundum.

Explanation:

Corundum is the hardest mineral in nature after diamond. For this reason it can only be scratched and worked by it. Mohs' hardness scale proves that corundum is indeed a very hard mineral and almost impossible to scratch. This scale states that the corundum has a hardness of 9.0, which indicates that it cannot be scratched by a drill.

Using the same scale, we can find out the hardness of the mineral exposed in the question. The mineral can be scratched by a drill, which means it has a hardness lower than 8.5, and the mineral cannot be scratched by a nail, which indicates that it has a hardness greater than 6.5. Based on this data, we can guarantee that this meniral is softer than the corundum.

given:

mass of na = 115 g

excess cl2

to determine:

mass of nacl produced

explanation:

given reaction is-

2na(s) + cl2(g) → 2nacl(s)

since cl2 is in excess, na will be the limiting reagent

as per the reaction stoichiometry na: nacl = 1: 1

i.e. moles of na reacted = moles of nacl formed

now, # moles of na = mass of na/atomic mass

                                  = 115 g/23 g.mol-1 = 5 moles

therefore, moles of nacl = 5

molar mass of nacl = 58 g/mol

mass of nacl = 5 moles * 58 g.mol-1 = 290 g

ans: amount of nacl produced = 290 g