Which period contains elements that are all gases at stp

Period 1

Explanation:

Periods are the horizontal rows in the periodic table. They contain elements with the same number of electron shells. Period 1 has just two elements which are hydrogen (H) and helium (He). These two elements are gases at stp.

Hydrogen is a diatomic element that exist as gas at STP while helium is a monoatomic element that exist as a gas at STP. Hydrogen is found in group 1 and period 1 of the periodic table. Helium is found in the group zero of the periodic table - elements in group zero are called noble/rare/inert gases. Though, helium has just two electrons, its two electrons however completely fill its one and outermost shell which makes it "eligible" to be in the group zero.      

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be