Answer:
Primary and secondary waves both are body waves of seismic waves. Primary waves or pressure waves are compression waves and secondary waves are shear waves. These waves are represented by P and S waves respectively.
Differences:
P waves are smaller in size but travel faster, however, cause less damage whereas S waves are greater in size cause more damage, and travel slower.
P waves move in a push-pull pattern and travel through different mediums like solids, liquids, and gases, whereas S waves move in an up-and-down pattern and travel only through one medium that is a solid medium.
Answer: Reducing the activation energy can increase the rate of a reaction.
Explanation:
Activation energy is the extra energy that must be supplied to reactants in order to cross the energy barrier and thus convert to products.
A catalyst is a substance which increases the rate of a reaction by taking the reaction through a different path which involves lower activation energy and thus more molecules can cross the energy barrier and convert to products leading to increased rate of reaction.
Thus a catalyst speeds up the reaction by decreasing the activation energy.
Answer:
The correct option is A. Measuring radioactive decay of element isotopes
Explanation:
At the time of formation of rock, certain kinds of radioactive isotope elements get trapped in the rock. These radioactive isotopes are unstable and decay over a period of time forming daughter elements. A rock which will have more number of radioactive elements will be newer to a rock containing non-radioactive daughter elements.
The radioactive decay of each element can be measured by the half-life of elements. This is the primary technique to determine the absolute age of a rock.
Deoxyribose nucleic acid (DNA)