A zookeeper predicted the weight of a new baby elephant to be 272 pounds when it was born. The elephant actually weighed 304 pounds at birth. What was the percent error of the zookeeper’s prediction?

12.4%

Explanation:

The percent of error can be found by dividing the difference in weights by the predicted weight.

290 - 258 = 32 pounds

32/258 = 0.124

0.124 = 12.4% approximately was the percent of error

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

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.