Answer:
C.KEEPS YOU FROM ILLNESS
Explanation:
THE WORD IMMUNE MEANS TO PROTECT THUS THE IMMUNE SYSTEM IS TO PROTECT YOUR BODY AGAINST PATHOGENS AND DEASISES CAUSING GERMS....
Answer:
When the hammer is in the sun, heat flows by radiation
When you pick up the hammer, heat flows by conduction
Explanation:
As the hammer lies in the sun, heat is transferred to the hammer by radiation. Heat energy reaches the earth from the sun by radiation. Radiation is a mode of beat transfer in which heat is transferred without a material medium.
When you pick up the hammer, heat flows to your hand by conduction because your body is a conductor of heat.
The true statement is (A) energy is absorbed during the reaction
For the products to have more energy, they must absorb it from the surrounding.
Answer:
The empirical formula is ZnO2
Explanation:
What is the empirical formula for a compound which contains 67.1% zinc and the rest is oxygen?
Step 1: Data given
Suppose the compound has a mass of 100.0 grams
A compound contains:
67.1 % Zinc = 67.1 grams
100 - 67.1 = 32.9 % oxygen = 32.9 grams
Molar mass of Zinc = 65.38 g/mol
Molar mass of O = 16 g/mol
Step 2: Calculate moles of Zinc
Suppose the compound is 100 grams
Moles Zn = 67. 10 grams / 65.38 g/mol
Moles Zn = 1.026 moles
Step 3: Calculate moles of O
Moles O = 32.90 grams / 16.00 g/mol
Moles O = 2.056 moles
Step 4: Calculate mol ratio
We divide by the smallest amount of moles
Zn: 1.026/1.026 = 1
O: 2.056/1.026 = 2
The empirical formula is ZnO2
To control this we can calculate the % Zinc for 1 mol
65.38 / (65.38+2*16) = 0.67.1 = 67.2 %
The answer is (2) KNO3. This depends on the solubility of these four compounds at 10℃. For NaCl, it is 35.8 g, For NaNO3, 80.8 g. KCl, 31.2 g. KNO3, 21.9g. So only KNO3 is less than 25.0 g.
