1) Explain the term Aliquot and Diluent?

• Aliquot: It is a measured sub-volume of the original sample
• Diluent: Material with which sample is diluted

He has written over sixty books covering all aspects of testing. Answers and explanations, where necessary, are provided and you should.

2) What is molality?

Molality is the number of solutes that are present in 1 kg of a solvent.

3) What is titration?

Titration is a process to determine the molarity of a base or an acid. In this process, a reaction is carried out between the known volumes of a solution with a known concentration, against the known volume of a solution with an unknown concentration.

4) What is a buffer?

A buffer is an aqueous solution which has highly stable pH. It is a blend of a weak acid and its conjugate base or vice versa. On adding a small amount of base or acid to buffer, its pH hardly changes.

5) How does buffer work?

In buffer when hydrogen ion is added, it will be neutralized by the base in the buffer. Hydroxide ion will be neutralized by the acid. On the overall pH of the buffer solution, these neutralization reactions will not show much effect.

While when you select an acid as a buffer solution, try to use an acid that has a pH closed to your desired pH. This will help your buffer to achieve a nearly equivalent amount of acid and conjugate base, so that it will enable to neutralize as much as H+ and OH -.

6) What is a mole?

Mole is the unit used to define the number of chemical substance present in a substance. It is the amount of substance which consists of the same number of chemical units as there are atoms in exactly 12 gram of pure carbon-12.

7) How will you calculate how many moles of glucose present in 320 mL of 5.0 M of glucose solution?

First step: Convert the volume from millilitres to litres

• 320 X (1 litre/1000mL) = 0.320 L solution

Second use the formula = M x V

= 5.0 moles glucose/ litre solution X 0.320 L solution

= 1.6 moles of glucose present in 320mL of solution

8) Explain what is the difference between fractionation and distillation?

Both methods are used to separate the components present in the solution based on the melting points

• Distillation: This technique is used when the boiling point of chemicals are different in the mixtures

• Fractionation: This technique is used when the boiling point of chemicals are close to each other in the mixtures

9) Mention the formula to calculate pH of a solution?

In order to calculate the pH of a solution you have to use the formula pH= -log [H+] or pH = -log [H3O+]

10) What is the difference between Molarity and Normality?

Both techniques are used to the amount of chemical present in the solution. However, they are almost similar but differs in

Molarity	Normality
– Molarity is used to know the total amount of molecules in a 1-liter solution	– Normality is used to know the total number of reactive units in 1 liter of solution
– It is expressed as moles of a compound per litre of solution	– It is expressed in equivalent per litre

11) What is Valency?

Valency is a property of groups or atoms, equal to the number of atoms of hydrogen that the group or atom could combine with or displace it in forming compounds.

12) Define Avogadro’s law?

According to Avogadro’s law, at the same temperature and pressure, an equal volume of gases contains the same number of molecules regardless of the chemical nature and physical properties.

Avogadro’s number = 6.023 X 10 (-23)

13) Explain what makes a molecule into organic molecule?

In a molecule when a hydrogen atom is less than the ratio of the carbon atom, then such molecules are referred to as an organic molecule.

14) Which metal is used to extract copper from the solution of copper sulfate?

Fe or ferrous is the metal that is used to extract copper from the solution of copper sulphate.

15) Explain what is the chemical composition of fat in the human body?

The fat found in the human body is mainly composed of

• Glycerides
• Glycerides+Phospholipids
• Glycolipids
• Phosphoinositides
• Tocopherol

16) What is the monomer of polyethylene?

The monomer of polyethylene is ethylene

17) What is the formula you will use to calculate how many milliliters of 5.5 M NaOH are required to prepare 400 mL of 1.5M NaOH?

To know the amount or volume of NaOH to prepare 400 mL of 1.5 M NaOH, we use formula

M1 X V1 = M2 X V2

V1 = M2 X V2/ M1

But before that we will convert 400 mL into litre = 0.4 L

5.5 X V1 = 1.5 M x 0.4 L

V1 = 1.5 M X 0.4L/ 5.5

V1= 0.10 L

V1 = 100mL

So, you need 100mL of 5.5 NaOH

18) Why graphite rod is used in nuclear reactor?

A graphite rod is used in a nuclear reactor allows un-enriched uranium to be used as a nuclear fuel.

19) Mention how many milliliters is equal to 1 liter and how many microliters is equal to liter?

• 1 millilitre = 0.001 litre
• 1 microliter = 0.0000001 litre

20) What is oxidation and reduction reaction?

• Oxidation = When there is a loss of hydrogen or electrons OR gain of oxygen is known as Oxidation reaction.
• Reduction = When there is a gain of hydrogen or electron OR loss of oxygen is known as a reduction reaction

Example of oxidation-reduction reaction is observed in the human body when an electron is transferred into the cell and oxidation of glucose take place from which we get the energy.

21) What does iron ore consist of?

Iron ore is consists of Fe2O3

22) Explain what is dextro-rotatory and levorotatory?

Levorotation and Dextrorotation are referred to the properties of plane polarized light when light rotates clockwise when it approaches the observer is then known as dextro-rotation, and when the light rotates anti-clockwise then it is referred as levorotation.

A compound which exhibits a dextro-rotation is referred to as dextro-rotatory and which exhibits levorotation is referred to as levorotatory.

Silicon valley tech companies are famous for asking some pretty crazy brain-teaser interview questions…

I wanted to find out exactly what these questions involve. And how difficult they are to answer.

I spent a day on Glassdoor.com and a few other sites to come up with the 8 hardest and most interesting interview questions out there.

And not just from any companies…We’re going to look at 4 tech giants known for having the toughest interviews:

1. Facebook

2. Google

3. Apple

4. LinkedIn

Time to see how many you can answer!

Facebook Brain Teaser Interview Questions and Answers:

Question 1:

A Russian gangster kidnaps you. He puts two bullets in consecutive order in an empty six-round revolver, spins it, points it at your head and shoots. *click* You’re still alive. He then asks you, “do you want me to spin it again and fire or pull the trigger again right away?” For each option, what is the probability that you’ll be shot?

Answer…

The key hint here is that the bullets were loaded adjacent to each other.

There are 4 ways to arrange the revolver with consecutive bullets so that the first shot is blank. These are the possible scenarios:

1. (xBBxxx)
2. (xxBBxx)
3. (xxxBBx)
4. (xxxxBB)

The other two scenarios would have meant you got shot on the first attempt. (BBxxxx) or (BxxxxB)

Now look at the second slot in those 4 possible scenarios above. Your odds of getting shot are 1/4 or 25%. (Only #1 would get you shot)

But if you respin… there are 2 bullets remaining and 6 total slots. 2/6 or 33%.

Question 2:

You’re about to get on a plane to Seattle. You want to know if it’s raining. You call 3 random friends who live there and ask each if it’s raining. Each friend has a 2/3 chance of telling you the truth and a 1/3 chance of messing with you by lying. All 3 friends tell you that “Yes” it is raining. What is the probability that it’s actually raining in Seattle?

Answer…

You only need 1 of your friends to be telling the truth for it to be raining in Seattle.

It’s fastest just to calculate the odds that all 3 are lying, and it’s not raining.

Each friend has a 1/3 chance of lying. Multiply the odds together… you get 1/27 (1/3 * 1/3 * 1/3).

We’re not done yet though… 1/27 is the probability that all 3 friends lied at the same time.

The probability that at least 1 told you the truth? 26/27 or around a 96% that it’s raining in Seattle.

Google Brain Teaser Interview Questions and Answers:

Question 3:

You have a 3 gallon jug and 5 gallon jug, how do you measure out exactly 4 gallons?

Answer…

We know we can’t get the final result in the 3 gallon jug. It’ll overflow. We need to end up with 4 gallons in the 5 gallon jug.

First fill the 3 gallon jug.

Then pour the 3 gallons into the 5 gallon jug.

Now the 3 gallon jug is empty, and the 5 gallon jug has 3 gallons in it.

Fill the 3 gallon jug again. Slowly pour into the 5 gallon jug. Only 2 gallons will fit because it already has 3. Now it’s full.

Exactly 1 gallon is left in the 3 gallon jug.

Dump out the 5 gallon jug.

Pour your 1 gallon into the 5 gallon jug.

Fill up the 3 gallon jug one more time and pour it into the 5 gallon jug! You have exactly 4 gallons (and possibly a job at Google)

Question 4:

Why are manhole covers round?

Answer…

Good news: If you’re tired of math questions this one will give you a break.

Manhole covers are round because it’s the only shape that cannot fall through itself. The cover can never accidentally fall down the hole.

Microsoft has been known to ask this question and according to Glassdoor.com, Google is asking this too now.

Apple Brain Teaser Interview Questions and Answers:

Question 5:

There are three boxes, one contains only apples, one contains only oranges, and one contains both apples and oranges. The boxes have been incorrectly labeled such that no label identifies the actual contents of its box. Opening just one box, and without looking in the box, you take out one piece of fruit. By looking at the fruit, how can you immediately label all of the boxes correctly?

Answer…

So, you know all 3 boxes are incorrectly labeled.

Go to the box labeled “Apples + Oranges.” Since the label is wrong, it must have one or the other.

This is the box to take one piece of fruit from. Whichever comes out is what that box contains. If you took out an apple, the box has only apples. If you took out an orange, vice versa.

Here’s where it gets tricky a bit tricky. But we’re almost done…

Let’s say you grabbed an apple. Move the “Apples” label over to that box. Now it’s correctly labeled.

You know the “Oranges” box is still labeled wrong (because all 3 were labeled wrong to start and you haven’t touched it). And you know it’s not “Apples”.

So it has to be “Apples + Oranges”.

The last box is “Oranges”.

The same process above would work if you had pulled out an orange at the start.

Question 6:

You have a 100 coins laying flat on a table, each with a head side and a tail side. 10 of them are heads up, 90 are tails up. You can’t feel, see or in any other way find out which 10 are heads up. Your goal: split the coins into two piles so there are the same number of heads-up coins in each pile.

Answer…

By pure coincidence… this is a trick my friend Mike showed me last summer. It blew my mind back then but hopefully it’ll make sense as I write it out.

You want equal number of heads in each pile. There are currently 10 of them. You don’t know which but it doesn’t matter. All you have to do… take any 10 coins out of the 100, put them into a separate pile, and flip those 10 over.

That’s pile #1.

Pile #2 is the remaining 90 coins, unflipped. Just leave them.

You’re done. Seriously.

You can do this with any number of coins. If you had 20 coins, and 18 were heads, you’d need to take 18 of them (it doesn’t matter which) into a separate pile and flip those 18. That’s pile #1.

If you had 10 coins and 3 were heads, you’d take 3 random coins into a new pile and flip those 3 for your first pile, and the rest are your second pile.

Crazy right?

If you don’t believe me just grab some pennies and try it.

There are no exceptions and it doesn’t need to be an even amount of “heads” to begin with either. It can also be zero. Or all.

LinkedIn Brain Teaser Interview Questions and Answers:

Question 7:

You’re in a room with three light switches, each of which controls one of three light bulbs in the next room. You need to determine which switch controls which bulb. All lights are off to begin, and you can’t see into one room from the other. You can inspect the other room only once. How can you find out which switches are connected to which bulbs?

Answer…

Let’s call the switches 1, 2, and 3.

Leave switch 1 off.

Turn switch 2 on for ten minutes.

Now turn it off and quickly turn on switch 3.

Go into the room and inspect…

The bulb that is still warm but not lit up is controlled by switch 2. The one that’s currently lit up is switch 3. The last one is switch 1.

Question 8:

How many golf balls would fit into a Boeing 747?

Answer…

This last one is tough, but they don’t expect you to get an accurate answer. If you get a question like this (and there are a ton of variations- basketballs in a room, cellphones in Manhattan, etc.) they want to see your thought process.

The hiring manager is going to look at how you work your way through it and attempt to figure it out.

If you can break a problem down into smaller pieces, stay calm, and get an answer that’s not perfect but reasonably close, you’ve done great.

They might not even know the answer. They just want to see how you approach something that’s very difficult.

Note: For 5 other major things every hiring manager wants to see, check out this article.

On a Practical Note, What Can You Take Away From This?

Question 8 above highlights a pretty good point to remember in your interviews…

There are a lot of questions in an interview where the hiring manager values your thought process. Sometimes more than a correct answer.

If you’re stumped, talk out loud a bit and explain what you’re thinking. Ask a question if you need to. Try to break it down into smaller pieces.

Specific knowledge can be taught but they can’t teach you problem-solving. Show them this and you have a great shot at getting hired!

I talk a lot about how to do this and why it’s important in my job interview answers guide.

Here’s a quick story: My degree is in Finance, which means I took a good amount of Accounting classes too. Early in my career I had a phone interview for an Accounting position.

To make the story short, I could not answer even the most basic accounting questions. Really simple stuff that you learn your first year in college.

Why?

It had just been too long since college and I had forgotten even the basics. And I didn’t prepare well for the interview obviously!

But I tried to stumble through it and remember what I could, talking about what I was thinking. Saying things like, “well, this can’t be right because….”

I made some progress. But I definitely didn’t have the right answer, even after 5 minutes grinding through it outloud.

But I got invited to come in and do a full day on-site interview the next day.

The hiring manager liked my approach to breaking down a problem that I didn’t immediately know how to solve. That’s why being transparent and showing your thought process is one of the tips for interviews that you’ll see me say over and over.

You can learn to do the same and get far more job offers.

The big takeaway: Don’t panic when you get a question you don’t know… use it as an opportunity to show exactly how you work through things. Be confident with it, relax, smile. Remember… you’re giving the hiring manager what they want!

UPDATE:

Puzzle Questions And Answers

If you have interviews coming up and don’t want to leave anything to chance, I’ve created a new guide where you can copy my exact step-by-step method for getting job offers. You can get more details here.

Best Interview Answers Pdf

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