CHEMISTRY HIGH SCHOOL

Which balanced equation represents an oxidation-reduction reaction?(1) BaCl2 + Na2SO4==>BaSO4 + 2NaCl
(2) C+H2O ==>CO + H2
(3) CaCO3==>CaO + CO2
(4) Mg(OH)2 + 2HNO3==>Mg(NO3)2 + 2H2O

Answers

Answer 1
Answer: Correct Answer: option 2 i.e. (2) C+H2O ==>CO + H2

Reason: 
Reaction is said to be oxidation-reduction (redox) type, when one species undergoes oxidation, while other species undergoes reduction. In present case, during the course of reaction, carbon is oxidized from '0' to '+2'. On other hand, hydrogen is reduced from '+1' to '0'.  
Answer 2
Answer: The answer is (2). The oxidation-reduction reaction means that there is electrons transfer in the reaction. So there is valence change of at least two elements evolving in the reaction.

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Which scientist first attempted to construct a periodic table based on an element's atomic mass? A. Mendeleev B. Newton C. Dalton D. Moseley

What is Neons group and periodic number?

Answers

Its a noble gas. Its group number is 18 period number is 2

Answer:Hello,

Neon is a noble gas. It is located Group 18 and the oxidation number is 10.

I hoped it helped have a nice day!

What is the maximum number of covalent bonds a carbon atom can form with other atoms?A. 1
B. 2
C. 4
D. 6

Answers

(C.) Each carbon atom in ethane forms 4
There is no such thing called a 'hexa-bond', as there is a quad-bond and a triple bond and so on...

A carbon atom cannot form a 6 covalent bond with another atom, the max is 4. 

Answer: 4

Which of the following compounds is least solublein water?
(1) copper (II) chloride
(2) aluminum acetate
(3) iron (III) hydroxide
(4) potassium sulfate

Answers

Iron (III) hydroxide is the least soluble compound as it has the lowest Ksp value.

What is solubility of a solute?

The solubility is the amount of solute that can dissolve in a given volume of solvent at a particular temperature.

The solubility of substances can be compared using their their solubility products constant (Ksp) values.

Iron (III) hydroxide has the lowest Ksp value.

Therefore, Iron (III) hydroxide is the least soluble compound.

Learn more about solubility at: brainly.com/question/24057916

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Answer:3

Explanation:

stated

What weight of oxalic acid dihydate must be measured to prepare 1 litre of 0.01 oxalic acid solution

Answers

The weight of oxegon

What is the mass percentage of carbon in 5.000 G of sucrose

Answers

Answer : The mass percentage of carbon in sucrose  is, 42.1 %

Explanation: Given,

Molar mass of C = 12 g/mole

Molar mass of H = 1 g/mole

Molar mass of O = 16 g/mole

First we have to calculate the molar mass of sucrose.

Molar mass of sucrose (C_(12)H_(22)O_(11)) = 12(12)+22(1)+11(16)=342g/mole

Now we have to calculate the mass of carbon in 5 g of sucrose.

As we now that there are 12 number of carbon atoms, 22 number of hydrogen atoms and 11 number of oxygen atoms.

The mass of carbon = 12* 12=144g

As, 342 g of sucrose contains 144 g of carbon

So, 5 g of sucrose contains (5)/(342)* 144=2.105g of carbon

Now we have to calculate the mass percentage of carbon in sucrose.

Formula used :

\%\text{ Mass percentage of carbon}=\frac{\text{Mass of carbon}}{\text{Mass of sucrose}}* 100

Now put all the given values in this formula, we get:

\%\text{ Mass percentage of carbon}=(2.105)/(5)* 100=42.1\%

Therefore, the mass percentage of carbon in sucrose  is, 42.1 %
17) 8.4 / 20 x 100

18) 20 . 0.5150

19) 6,50% because (as you said) the law of definite proportions states that regardless of the amount, a compound is always composed of the same elements in the same proportion by mass

In which reaction are electrons transferred from one reactant to another reactant?(1) 2Ca(s) + O2(g) =>2CaO(s)
(2) AgNO3(aq) + KCl(aq) =>AgCl(s) + KNO3(aq)
(3) HCl(aq) + NaOH(aq) =>NaCl(aq) + H2O(l)
(4) H3O+(aq) + OH-(aq) => 2H=O(l)

Answers

Answer : The correct reaction is, (1) 2Ca(s)+O_2(g)\rightarrow 2CaO(s)

Explanation :

(1) 2Ca(s)+O_2(g)\rightarrow 2CaO(s)

In this reaction, the oxidation state of calcium (Ca) changes from (0) to (+2) and the oxidation state of oxygen (O) changes from (0) to (-2). In this reaction the electrons are transferred from one reactant (calcium) to another reactant (oxygen). This is a synthesis reaction.

(2) AgNO_3(aq)+KCl(aq)\rightarrow AgCl(s)+KNO_3(aq)

In this reaction, there is no changes in the oxidation state of the elements. So, in this reaction, no electrons transferred from one reactant to another reactant. This is a double-displacement reaction.

(3) HCl(aq)+NaOH(aq)\rightarrow NaCl(aq)+H_2O(l)

In this reaction, there is no changes in the oxidation state of the elements. So, in this reaction, no electrons transferred from one reactant to another reactant. This is a neutralization reaction.

(4) H_3O^+(aq)+OH^-(aq)\rightarrow 2H_2O(l)

In this reaction, there is no changes in the oxidation state of the elements. So, in this reaction, no electrons transferred from one reactant to another reactant. This is a combination reaction.

Hence, the correct reaction is, (1) 2Ca(s)+O_2(g)\rightarrow 2CaO(s) in which the electrons transferred from one reactant to another reactant.
The answer is (1). The electrons transfer form one reactant to another means that there is the change of valence. For other choices, the valence of reactant does not change.
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