Explanation

Portable timekeeping device of great accuracy, particularly one used for determining longitude at sea

Explanation

Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert wrote De Magnete, in which he made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber.

Explanation

Trees release carbon dioxide at night and carbon dioxide being heavier than air descendes.So a person sleeping under a tree breathes carbon dioxide which is harmful for the human body.

Explanation

The zeroth law of thermodynamics states that if two thermodynamic system are each in thermal equilibrium with a third, then they are in thermal equilibrium with each other.

Explanation

A free-falling object has an acceleration of 9.8 m/s/s, downward 

Explanation

Xylem is one of the two types of transport tissue in vascular plants, the other being phloem.

The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients.

Explanation

"The branch of science concerned with the nature and properties of matter and energy.

The subject matter of physics includes mechanics, heat, light and other radiation, sound, electricity, magnetism, and the structure of atoms."

Explanation

In carbon dioxide molecule, a carbon atom is joined by four covalent bonds to two oxygen atoms, which have two covalent bonds each.

Explanation

Specificity of the codon is the redundancy of the genetic code, exhibited as the multiplicity of three base pair codon combinations that specified an amino acid

Explanation

Hydrogen and helium, the lightest two gases,

Hydrogen is a chemical element

It is colorless, odorless, tasteless, non-toxic, and highly combustible. 

Symbol: H

Atomic mass: 1.00784 u

Atomic number: 1

Atomic mass : zero

Boiling point: -252.9 °C

Discoverer: Henry Cavendish