Answer: the answer is True
Explanation:
A and B should be correct
Answer:
Preventing Unknown Chemicals
Label all chemical containers, including beakers, flasks, vials, and test tubes.
Immediately replace labels that have fallen off or that are deteriorated.
Label containers using chemical names. ...
Archived research samples are often stored in boxes containing hundreds of small vials.
Total weight of alloy is
67 + 20 = 87 g
67 g of which is gold
So % gold is 67/87* 100 = 77.01%
Answer:
c. Only certain energies are allowed for the electron in a hydrogen atom
Explanation:
Emission spectrum are produced when the excited electron in a atom release the energy in the form of photons to come to ground state. These photons are of different wavelengths depending on the excitation state of emitting electron or transition of electron. These electromagnetic radiation are observed through prism to produce the spectrum.
As the name indicates this spectrum is produced by emission of energy. Although the electron can be excited by different methods such as by heating but the key point is that electrons in hydrogen atom will emit the photons of same energy which they absorb and each electron can absorb only certain type of energy. So four lines were observed in the visible spectrum of hydrogen because only certain energies are observed for hydrogen atom.
