What do u mean by this
Like do u want the name of it?
Divide 50 miles an hour or mph by 0.621, should give you 80.51 kilometers an hour or km/hr, this being the speed limit on that street in km/hr. If you're going 120 km/hr on an 80.51 kilometers an hour road you are speeding, as you're above the speed limit.
Answer: The correct option is 2.
Explanation: Group 15 elements are Nitrogen, phosphorous, Arsenic, Antimony, Bismuth.
To know whether an element exits as a diatomic molecule or not, we look at the atomicity of an element.
Atomicity is the number of atoms of an element combining to form a molecule.
Atomicity of Nitrogen = 2
Atomicity of Phosphorous = 4
Atomicity of Bismuth = 1
Atomicity of Arsenic = 1
The element having atomicity 2 will exist as a diatomic molecule.
Hence, Nitrogen is a diatomic molecule 
Answer:
Correct answer is A, they regulated the ticking of the clock...
Explanation:
The atomic clock uses a more fundamental vibration, and it uses it as part of a self-regulating system. A crystal of quartz has two properties that help it keep time.
The atoms serve the same purpose as did pendulums or quartz crystals in earlier clocks. They have no “hands” to turn or liquid crystal displays for number read-outs. They simply produce electrical pulses that serve as a standard for calibrating other less accurate clocks.