Answer: b} The exact time when an individual atom will decay can be accurately predicted.
c} After each half-life, the amount of radioactive material is reduced by half.
Explanation:
All radioactive decay follows first order kinetics.
Rate law expression for first order kinetics is given by:
where,
k = rate constant
t = time taken for decay process
a = initial amount of the reactant
a - x = amount left after decay process
Expression for calculating half life, which is the time taken by the half of the reactants to decompose is:
Answer:
This is the first answer,
winter solstice
The winter solstice occurs during the hemisphere's winter. In the Northern Hemisphere, this is the December solstice (usually December 21 or 22) and in the Southern Hemisphere, this is the June solstice (usually June 20 or 21).
and this is the second one,
the tilt of the Earth on its axis
Seasons change because of the tilt of the Earth and the planet's movement around the Sun. Did you know? It takes about 365.25 days for the Earth to orbit the Sun. We have leap years to make up for the extra ¼ day!
Because it’s kinetic energy INCREASES the speed
MgCl₂ & PbSO₄ is the correct product for the given double replacement reaction.
<h3>What is double displacement reaction?</h3>
In the double displacement reaction displacement of two substrate will take place among two reactants and formation of products takes place.
In the question, PbCl₂ reacts with MgSO₄ and displacement between the cations takes place and formation of MgCl₂ and insoluble precipitate PbSO₄ is formed.
Given reaction is represented as:
PbCl₂ + MgSO₄ → MgCl₂ + PbSO₄
According to the activity series, reactivity of Magnesium is more as compared to the lead atom. So lead is displaced by the magnesium atom and form the above given products.
Hence, option (3) is correct i.e. MgCl₂ & PbSO₄.
To know more about double displacement reaction, visit the below link:
brainly.com/question/26413416
Answer:
Explanation:
An element with atomic number 18 is a noble gas.
The element with atomic number 19 will have one extra electron so it can donate one electron or shed one electron to attain noble gas configuration .
It tends to shed one electron to become positively charged ion . Hence they are electro-positive elements .
Similarly the element with atomic number 17 will have one short electron so it can gain one electron to attain noble gas configuration .
They tend to gain one electron to become negatively charged ion . Hence they are electro-negative elements . They have high electronegativity .
