Students are conducting an experiment to determine if sugars are present in foods. They heat a test tube containing a sugar solution in a beaker of water. Which of these is an UNSAFE laboratory practice in this experiment? a. heating the sugar solution in a closed test tube
b. rinsing hands with water after handling the materials
c. using a test tube clamp to hold the test tube
d. wearing safety goggles while heating the sugar solution

A

Explanation:

Benedict's test is the ideal standard test to distinguished between reducing(glucose) and Non reducing(diasaccharides,sucrose).

Benedict's tests gives a positive test for the presence of reducing sugar,with the initial mixture of the sugar solution changing from  the initials green and orange  color   and brick red precipate of copper (ii) ,which would not dissolve in solution.

However, with non reducing the Benedict's gives a negative test.Because no color change occurs.

In either case,the chemical reaction that occurs as the solution gained heat  is exothermic and this may lead to boiling of the solution and spilling onto the burner,which may lead to explosion.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.