Answer:
OPTION (A) : Testing a rock sample for gold content
Explanation:
For testing a rock sample of gold content you will need a Chemist. To test the material, the sample is rubbed on black stone which will leave a mark on the stone. This mark is tested by applying aqua fortis i.e nitric acid on the mark. If the mark gets dissolve then the material is not gold. If the mark sustain the it is further tested by applying aqua regia i.e nitric acid and hydrochloric acid which will prove the sample is of gold if it gets dissolve on using hydrochloric acid. The purity of the sample can be checked by differing the concentration of the aqua regia and comparing it with the gold material of the known purity.
<u>Answer: </u>The correct answer is Silver.
<u>Explanation:</u>
Specific heat of fusion is defined as the amount of heat which is required to raise the temperature of 1 gram of a substance to 1°C. It is generally expressed in kJ/mol
We are required to find the substance which require more heat. For that we need to know the specific heat of all the substances.
The substance which have the highest specific heat, will require more heat.
The specific heat of the given substances are:
Silver = 11.3 kJ/mol
Sulfur = 1.7175 kJ/mol
Water = 5.98 kJ/mol
Lead = 4.799 kJ/mol
The specific heat of silver is the highest and hence, will require more heat.
Hence, the correct answer is silver.
<h3>Question :</h3>
The use of genetics by farmers to produce more abundant and healthier crops is an application of the science of _____.
<h3>Answer :</h3>
The use of genetics by farmers to produce more abundant and healthier crops is an application of the science of <u>biotechnology</u>.
So correct option is 2nd biotechnology.
<h3>Explanation :</h3>
Biotechnology is the use of biological structures and processes for useful industrial purposes, whether product or function.
Method 1: gravimetry
advantages: Impurities in the sample can be identified
disadvantages: The process is long, because it goes through several stages
Method 2: titration
advantages: the process is fast, because the titrate and titrant react immediately
disadvantages: Sometimes the determination of the end point of the titration is carried out too fast or too slowly so that the calculations carried out are inaccurate
Answer:
Demo Mole Quantities
58.5g NaCl(mol/58.5g)(6.02 x 1023/mol) = 6.02 x 1023 Na
+
Cl21 pre-1982 pennies (after 1982 pennies are mostly zinc with copper coating)
63.5g Cu( mol/ 63.5g)(6.02 x 1023/mol) = 6.02 x 1023 Cu
19.0g Al (mol/27.0g)(6.02 x 1023/mol) = 4.24 x 1023 Al
Explanation:
