Which of the statement(s) given above is/are correct? 
1. Kevlar-coated nanotubes are being used as a replacement for natural joints.
2. Nano-silicate particles can replace burnt skin. 
Select the correct answer using the codes below: 

How can the height of a person who is six feet tall be expressed (approximately) in nanometres?

There is some concern regarding the nanoparticles of some chemical elements that are used by the industry in the manufacture of various products. Why? 

$1$. They can accumulate in the environment, and contaminate water and soil.
$2$. They can enter the food chains.
$3$. They can trigger the production of free radicals.  

 Select the correct answer using the code given below:

With reference to the use of nanotechnology in the health sector, which of the following statement(s) is/are correct?
1. Targeted drug delivery is made possible by nanotechnology.
2. Nanotechnology can largely contribute to gene therapy.
Select the correct answer using the code(s) given below: