Answer:
A reaction rate is a measure of how fast a reactant disappears or a product forms during a reaction.
Explanation:
It is usually defined as the change in concentration per unit time:
Δ(concentration)/Δt
The units are (moles per litre) per second.
In symbols, the units are mol/(L·s) or mol·L^-1 s^-1.
Answer:
The correct option is b. false
Explanation:
The distance between the nucleus of an atom and it's outermost shell is called is atomic radius. The atomic radius of an Iron atom (Fe) is 0.126 nm or 1.26 angstrom. The distance between the nuclei of two Iron atoms will be 1.26 × 2 = 2.52 angstroms.
Since 2.52 angstroms is lower than 4 angstroms, the correct option is false
Answer:
Cloudy nights can be warmer than clear nights because clouds trap heat absorbed by Earth during daylight hours.
Answer: a) 
b) 
c) 
d) 
Explanation:
General representation of an element is given as:_Z^A\textrm{X}
where,
Z represents Atomic number
A represents Mass number
X represents the symbol of an element
Mass number is defined as the sum of number of protons and neutrons that are present in an atom.
Mass number = Number of protons + Number of neutrons
In an atom, when neutrons or protons are lost or gains, it directly affects the mass number of an atom.
Atomic number is defined as the number of protons or number of electrons that are present in an atom.
It is characteristic of a particular element.
Atomic number = Number of electrons = Number of proton
a) Z 74, A 186: 
b) Z 80, A 201: 
c) Z 34, A 76: 
d) Z 94, A 239.: 