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Ever wondered why nitrogen in the liquefied form is used in medical applications? Or why your grandmother often falls ill?
Well, these were some of the questions asked by Topper readers to our panel of experts.
This week we feature four questions asked by Class X students, along with the answers!
Subject: Mathematics
Q. Show that one and only one of p, p+2 or p+4 is divisible by 3.
Posted by: SITHARA
A. Suppose p is divisible by 3 then p=3q (say) where q is some non negative integer.
The next multiple of 3 will be only p+3,p+6 etc( multiples of 3 will occur only after a gap pf 3)
So, if p is a multiple of 3 then p+2 and p+4 can't be multiples of 3
Next if p+2 is a multiple of 3 then p+2= 3r(say)
So, the multiple of 3 before p+2 must be (p+2)-3 and the next mutiple after p+2 will be (p+2)+3 ie p-1 and p+5 respectively. So if p+2 is a multiple of 3 then por p+4 can't be multiples of 3.
By a similar logic, we can show that if p+4 is a multiple of 3 then p or p+2 can't be multiples of 3.
This explains the answer.
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Subject: Chemistry
Q. Give reason why nitrogen in the liquefied form finds utility in medical applications such as preserving biological sample!
Posted by: Gpriya
A. At atmospheric pressure, liquid nitrogen boils at 77 K (−196 °C; −321 °F) and is a cryogenic fluid, thus finding utility in the medical applications like cryopreservation of blood, reproductive cells (sperm and egg), and other biological samples and materials.
Subject: Physics
Q. A car travels a certain distance with a speed of 50 km/hr and returns with a speed of 40 km/hr. How do I calculate the average speed for the whole journey.
Posted by: Meghagrao
A. Let the first car took t1 hrs to complete the journey similarly second car took t2 hrs ,and consider the distance between them is x kms.
Now 50 t1 = 40 t2 from this find the value of t1 in terms of t2
Use average speed = total distance / total time taken = 2 x / t1 + t2 ----------------- (1)
Again put the value of x = 40 t2
Put the value of x, in the (1) equation and find the answer.
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Subject: Biology
Q. Why do old people fall ill?
Posted by: Shreyaj
A. This is due to ageing. Ageing is a continuous process that restricts our normal body functions and makes us more prone to diseases. Aging results due to a complex interaction of genetics, chemistry, physiology and behaviour.
