<h2>Answer : Option C) Joseph is observing the color of the reaction mixture to see whether proteins are present in the given solution.</h2><h3>Explanation :</h3>
An example of qualitative observation is the one where one uses the five senses to identify the changes in the reaction.
Here, when Joseph is studying a reaction mixture he is trying to observe a color change which will confirm that there is proteins present in the reaction mixture or not If there is a color change observed then it will confirm the presence of proteins.
Usually qualitative observations are those which can be easily predicted by using five senses.
Answer: The amount of water produced is 9.3 grams
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.

mass of reactants = mass of methane + mass of oxygen = 22.5 g + 35.7 g = 58.2 g
mass of products = mass of carbon dioxide + mass of water = 48.9 g + mass of water
48.9 g + mass of water = 58.2 g
mass of water = 9.3 g
Answer:
Approximately 1.9 kilograms of this rock.
Explanation:
Relative atomic mass data from a modern periodic table:
To answer this question, start by finding the mass of Pb in each kilogram of this rock.
89% of the rock is
. There will be 890 grams of
in one kilogram of this rock.
Formula mass of
:
.
How many moles of
formula units in that 890 grams of
?
.
There's one mole of
in each mole of
. There are thus
of
in one kilogram of this rock.
What will be the mass of that
of
?
.
In other words, the
in 1 kilogram of this rock contains
of lead
.
How many kilograms of the rock will contain enough
to provide 1.5 kilogram of
?
.
Answer:
1
all matter is made of tiny particles called atom