Explanation:
a) Both A and R are true and R is the correct
explanation of A.
In this case, according to the given information about the oxidation numbers anf the compounds given, it turns out possible to figure out the oxidation number of manganese in both MnI2, manganese (II) iodide and MnO2, manganese (IV) oxide, by using the concept of charge balance.
Thus, we can define the oxidation state of iodine and oxygen as -1 and -2, respectively, since the former needs one electron to complete the octet and the latter, two of them.
Next, we can write the following 
, since manganese has five oxidation states, and it is necessary to calculate the appropriate ones:
Next, we multiply each anion's oxidation number by the subscript, to obtain the following:
Thus, the correct choice is Manganese has an oxidation number of +2 in Mnl2 and +4 in MnO2.
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Answer:
B. pour the reagent into a small beaker before using it
Explanation:
Let's explore all the mentioned practice
A. Leftover reagents should not be discarded in the sink but discarded according to the disposal method present in the safety data sheet (SDS) of the chemical.
B. Reagents should be poured in a clean beaker for use to avoid contamination in the original reagent bottle
C. This is not a good practice, as the plastic pipet tends to contain some impurity in its tip.
D. This is also a bad practice. Firstly, a reagent should be taken according to the need. If there is leftover, it should be discarded as it most probably contains contamination in it
Answer:
The accuracy can be improved by making sure no external force is applied, i.e the marbles should accelerate under gravity only during each trial.
Explanation:
Accuracy is a term used to describe the relationship between a measured value to the real value. When a measured value is accurate, it implies that there is little or no error in the value; thus it is equal to the real value or very close to it.
Since this experiment is to determine the speed with which the marble roll down the plane, they should ensure uniform acceleration through out the trials. The marbles should be allowed to move under the influence of gravity only without applying any external force.
