The answer is D, Magnesium.
For an anion or cation(negatively or positively charged ion) to replace a similarly-charged ion, it needs to be more active. This means that only a cation that is above Zinc on the reactivity scale can replace Zinc.
Since Aluminum was displaced in the reaction, that means the unknown metal is more reactive.
This means that our options are:
Lithium, Potassium, Calcium, Sodium, and Magnesium.
But because the metal did not displace the Sodium, it must be less reactive than it.
This gives us a new list of metals that are less-reactive than Sodium:
Magnesium, Aluminum, Zinc, Iron, Nickel, etc.
The only metal on both lists is Magnesium, and that means that your answer is D, Magnesium.
The overall order of a reaction is directly
related to the reaction mechanism of the reaction. The reaction mechanism is
defined by the reaction rate equation. In this case, we are given by the
equation, Rate=k. The order of this reaction is zero since the rate is
not dependent on the concentration of reactants or products.
Strong acid on combining with strong base will always give neutral solutions. Consider the following example for the same
HCl + NaOH ↔ NaCl + H2O
(strong (strong
acid) base)
In above case, the resultant solution is neutral in nature.
On other hand, weak acid will react with strong base to form salt and water. But the solution will be basic in nature. Also, strong acid will react with weak base to form salt and water. But the solution will be acidic in nature
Answer:
1. a chemical reaction in which one substance breaks up into two or more new substances: decomposition reaction
2. a reaction in which two or more substances combine to form a new substance: synthesis reaction
3. the reaction of an acid with a base to form a salt and water: neutralization reaction.
4. chemical compound formed when the negative ions from an acid combine with the positive ions of a base: salt
5. two ionic compounds reacting in solution to form two new compounds, one of which is insoluble: double displacement reaction.
6. a reaction in which an active metal displaces a less active metal or hydrogen from a compound solution (or a nonmetal replaces a nonmetal from a compound in solution): Single replacement reaction
Explanation:
1. Decomposition is a type of chemical reaction in which one reactant gives two or more than two products.
Example: 
2. Synthesis reaction is a chemical reaction in which two reactants are combining to form one product.
Example: 
3 and 4. Neutralization is a chemical reaction in which an acid and a base reacts to form salt and water. Salt is formed when cations or positive ions of base combine with anions or negative ions of acid.
Here 
is the salt formed by combination of 
from base and 
from acid.
Example: 
5. A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.
Example: 
6. Single replacement reaction is a chemical reaction in which more reactive element displaces the less reactive element from its salt solution.
Example: 
Answer:
Option 2 is correct.
Scintillation counters and Geiger Counters provide instantaneous measure of radioactivity.
Explanation:
Of the three means of measuring radioactivity presented. Only Film-badge dosimeter lacks a sensitive photo-detector piece that instantaneously converts the amount of radiation seen into electrical waves. It collects the radiation over time and the film is then developed after a particular point in time for the radioactivity collected to be measured.
Although used majorly for gamma rays and neutrons, the scintillation counters uses a scintillator to convert ionizing radiation (like the two mentioned at the start of this passage), into photons that the photo-detector (usually very sensitive) converts into electrical signals for immediate reading. It gives the energy and intensity of the radiation intended to.be measured.
The Geiger Muller counter, the most used measure of radioactivity across all fields, uses the tube (which contains inert gases) as the sensitive radiation detecting piece. High voltage maintained in the tube makes the gases conductive and it transmits the intemsity of radiation to the processing part of the counter which converts this reading to electrical signals, immediately for reading. Unlike the scintillation counters, it doesn't measure the energy of the radiation.
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