When is it necessary to where safety glasses in the laboratory? A pipette has a

Question

When is it necessary to where safety glasses in the laboratory?

A pipette has a designated volume of 20.00 mL.A student uses the pipette to deliver three aliquots of water and determines the mass of each as follows:

20.0119 g

20.0009 g

20.0109 g

Calculate the relative spread of these masses and select the correct answer from the list below.

Select one:

a. 0.00055%

b. 0.011%

c. 0.055%

d. 20.0079%

How many valence electrons are present in a chlorine atom?

- Chloroform has molecular formula of CHCl3 . Which of the statements is correct?

Select one:

a. The molecule will have be linear.

b. Carbon forms triple bonds with chlorine.

c. The molecule will be planar.

d. The molecule will not contain double bonds present.

The 3D shape of one of the following molecules is influenced by the presence of lone pairs of electrons. Select the correct option.

Select one:

a. Chloroform, CHCl3

b. Acetylene, C2H2

c. Methanol, CH3OH

d. Methane CH4

-

What colour would you expect a solution of 0.001 M HCl to be after the addition of one drop of universl indicator?

Select one:

a. light green

b. pink

c. very pale yellow

d. peach

Explanation / Answer

Q1. Wearing safety glasses should be made a habbit while working in lab. Safety glasses should always be worn while dealing with acids bases active metals like Na, while studying exothermic reactions etc.

Q2. Relative spread =[ (highst value - lowest value)/ highst value] ×100 =( 20.0119 - 20.0009 / 20.0119)×100 = 0.055%

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