Which of the following reactions are redox reactions? which of the following reactions are redox reactions? ca(s)+cl2(g)→cacl2(s) hcl(aq)+naoh(aq)→h2o(l)+nacl(aq) zn(s)+fe2+(aq)→zn2+(aq)+fe(s) ba(no3)2(aq)+k2so4(aq)→baso4(s)+2kn o3(aq)

Answer :  The redox reactions are:

Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

(1)

This reaction is a redox reaction.

In this reaction, the oxidation state of 'Ca' changes from (0) to (+2) that means 'Ca' lost 2 electrons and it shows oxidation reaction and the oxidation state of 'Cl' changes from (0) to (-1) that means 'Cl' gain 1 electron and it shows reduction reaction.

(2)

This reaction is a double-displacement reaction in which the cation of two reactants molecule exchange their places to give two different products.

In double-displacement reaction, the oxidation state of cation and anion remains same on both side of the reaction. So, it is not a redox reaction.

(3)

This reaction is a redox reaction.

In this reaction, the oxidation state of 'Zn' changes from (0) to (+2) that means 'Zn' lost 2 electrons and it shows oxidation reaction and the oxidation state of 'Fe' changes from (+2) to (0) that means 'Fe' gain 2 electron and it shows reduction reaction.

(4)

This reaction is a double-displacement reaction in which the cation of two reactants molecule exchange their places to give two different products.

In double-displacement reaction, the oxidation state of cation and anion remains same on both side of the reaction. So, it is not a redox reaction.

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noun

the practice of taking someone else's work or ideas and passing them off as one's own.

explanation:

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.