IGCSE Chemistry Paper1: Specimen Questions with Answers 25  26 of 99
Question number: 25
Question
Which structure is incorrect?
Choices
Choice (4)  Response  

a. 
 
b. 
 
c. 
 
d. 

Answer
c.Explanation
The electronic configuration of carbon is (2,4) and that of hydrogen is 1.
In Figure C, C have four electrons to bond with. If it bonds with three H atoms then there is no possibility to combine with two C atoms. Therefore C is incorrect.
Question number: 26
Question
To grow tulip, a fertiliser containing nitrogen, phosphorus and potassium is used. For the best tulip flowers, the fertiliser must have high proportion of potassium.
Which fertiliser is best for producing tulips?
Choices
Choice (4)  Response  

a.  fertiliser proportion by mass N is 29, P is 5 and K is 0 

b.  fertiliser proportion by mass N is 29, P is 15 and K is 5 

c.  fertiliser proportion by mass N is 13, P is 13 and K is 20 

d.  fertiliser proportion by mass N is 9, P is 0 and K is 25 

Answer
c.Explanation
Nitrogen, Phosphorous and Potassium and Potassium are the three major ingredients required by all plant materials, in varying proportions, dependent upon the plant’s needs. Fertilizers, by law, have a numerical NPK ratio printed on the container.
All the three are equal important. Roses utilize each ingredient at differing times of the growth and blooming cycles. More Nitrogen is needed for early spring growth of stems
Phosphorus moves very slowly in the soil, so applications are available only to feeder roots within a few inches of the soil surface. Continued use ensures that a supply of phosphorus will eventually reach the lower root structures, provided the soil Ph is proper.
Potassium also moves slowly and is not readily leached from the soil. However, it is extremely mobile within the plant system, where it can be leached from the leaves (its primary destination), by rainor irrigation. A continual supply of potassium is good practice.