Which of the following is not found in the nucleus of an atom?
a. electron
b. neutron
c. proton
d. quark

the answer is epidemic

the positively charged particles in the nucleus pull the negatively charged electrons. when we move from left to right, the number of protons increases then more protons attract negative charges, so electronegativity increases. this happens due to a greater charge on the nucleus which makes electron bonding pairs to be very attracted to atoms located more right on the periodic table. fluorine is the most electronegative element which is present in seventh group known as halogen group.

answer:

a)  

step-by-step explanation:

the ability of a substance to be ground into a fine powder is a physical property. thus, it belongs in a.

that eliminates c, which represents chemical properties.

it also eliminates b, the intersection of physical and chemical properties.

answer: - molecules.

solution: - the grams of tetrabromomethane are given and it asks to calculate the number of molecules.

it is a two step unit conversion problem. in the first step, grams are converted to moles on dividing the grams by molar mass.

in second step, the moles are converted to molecules on multiplying by avogadro number.

molar mass of   = 12+4(79.9)   = 331.6 g per mol

let's make the set up using dimensional analysis:

= molecules

so, there will be molecules in 250 grams of .