Each 2x10 will support 1,200 lbs.
So, 2x10 joists at 16” on center will support say live load (people and furniture) of 40 lbs. per square foot plus a dead load (framing, ducts, etc.) of 10 - 14 lbs. per square foot, depending on the species and grade of lumber.
The Codes allow for a 2×6 joist to support 53lbs per linear foot, which means an 8.5-foot length could support approximately 450-pounds across that length.
2 Answers. 2x6 joists at the span that you are talking about (16' and 18') are not strong enough to support a floor as a living space. With a span like that the timber size that you sister in would have to be at least 2x10's.
Because the O2 molecule has two unpaired electrons, it is paramagnetic.
Since C2 has no unpaired electrons, it is diamagnetic.
Since C2 has no unpaired electrons, it is diamagnetic.