Chemistry test results are in

_Elsa_

A couple of days later Philippe is ready to head back to class.  Bright and early the next morning they are both on the school bus heading towards class. Jean-Luc tells them that the chemistry test results might be handed out today. Philippe thinks that he might have done pretty well on the make-up test. Let’s find out …………….

 

“Good morning everyone” says Mr. Brown.  “I have your test results here so let me hand your papers back to you.  Philippe I see that you are feeling much better.” 

Philippe has a big smile on his face.  He is really enjoying the chemistry class.  The best part that he really loves is doing the lab when he can combine the chemicals together and watch what happens. 

“You all did very well on the test,” says Mr. Brown.  “I was pleasantly surprised to see how far you have all come since the first day of class.  Let’s go over the results together.” 

They go over each question and Mr. Brown gives them more information as to why each answer is correct.

1. One of the essential minerals in the human body is salt. How much salt (NaCl) is in the average adult human body?

250 grams - The average adult human body contains about 250 grams of salt, which is just over half a pound. If you don't have enough salt, your body suffers an electrolyte imbalance called hyponatremia.

2. If you fill a glass to the brim with ice water and the ice melts, what will happen?

The water level will drop slightly as the ice melts - One interesting property of water is that it achieves maximum density as a liquid, not as a solid. So, ice is less dense than water and floats. When it melts, it becomes more dense. More mass per unit volume means the level of the liquid drops slightly.

3. The symbol Sb stands for stibnum or stibnite. What is the modern name of this element?

Antimony - Stibnum is the old name for antimony. Be careful you don't confuse the symbol with Sn for tin (a common tricky chemistry test question). Tin is safe enough to use to make cans for food. Antimony and most of its compounds are toxic.

4. Water-based liquids can be described as acidic, neutral, or basic, with respect to pH. Which of these describes milk?

Slightly Acidic - Milk is close to a neutral pH, but it's slightly acidic thanks in part to the lactic acid it contains.

5. DNA codes for proteins, which are the building blocks of organisms. What is the most abundant protein in the human body?

Collagen - You'll find keratin primarily in your hair, nails, and skin, but the most abundant protein in humans is collagen, which is found in bone and cartilage. Both proteins are strong and flexible.

6. Noble gases are inert because they have completed outer electron shells. Which of these elements isn't a noble gas?

Chlorine - Chlorine is not a noble gas. It's one electron shy of a full octet, so unlike the noble gases, it's highly reactive.

7. What is the most common isotope of hydrogen?

Protium - Most of the hydrogen in the world is protium (one proton, no neutrons), but some deuterium and tritium occurs, too. Tritium is radioactive. Deuterium is not radioactive and is the form of hydrogen found in heavy water.

8. You can't live without water! What is its chemical formula?

H2O - You didn't miss this one, right? Water is good old H 2 O!  

9. Who is credited with the invention of the modern periodic table?

Mendeleev

Mendeleev (sometimes spelled Mendeleyev) is credited with creating the modern periodic table, although his table was based on increasing atomic mass rather than atomic number. Mendeleev's table grouped elements according to common properties and periodic trends.

10. Which of these elements is a nonmetal?

Sulfur - Sulfur is a nonmetal. It's yellow and lacks a metallic luster. (Info here)

Just as Mr. Brown finishes the last question the school bell rings. Now it’s time to learn all about DNA and identical twins. The two of them have been waiting forever to learn more about this. 

Let’s continue here - Hooray, time to learn more about genetics!

Start at the beginning – School days, school days ……….

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