One of the most important characteristic of a metal is its density. As density is the mass of any substance per unit volume. If one can measure the mass of the given shiny metal and its volume then the density of the metal can be determined. The density if matches with the density of the real gold then one can determine the metal is gold or not. The other experiments given will not work in any condition as-
1. Gold doesn't react with water.
2. The hardness of any metals are more than the non-metals and it is not at all an unique property of any metal.
3. All the metals usually reacts with acids or bases with more or less extent. thus it cannot identify the metal is gold or not.
4. The magnetic property is an inherent property of metal. There are several metals which shows magnetic property. Thus gold cannot be identified by this way.
Hello Norgepr, examples of failed experiments that produced valuable information
can be the mage via BoingBoing
There have been ample stories of human children being raised by other
species and eventually becoming more like that animal than an actual
human. If the process could go one way, Winthrop Kellogg was sure that
it could also go the other, particularly if the animal involved was one
of our closest genetic cousins. In 1931, Kellogg received a grant for
his experiment and the timing couldn’t be better –his wife just had a
baby boy, David. This would give them the unique opportunity to raise a
baby chimp, named Gua, right along side a human baby. It didn’t take
long for the babes to bond and become best friends. Kellogg and his
wife took impeccable notes on their two “children” noting their physical
changes, emotions and how they scored on small intelligence tests. The
chimp scored notably higher on the intelligence tests due the fact that
the species matures faster than human babies. Gua picked up quite a few
human behaviors, such as walking upright and eating with a spoon, but
she failed to learn how to speak and learn simple repetition games, like
patty cake. Her emotions were also much less predictable and inclined
to change at the drop of a hat. Unfortunately, the experiment really
started to go wrong when little David started to become more chimplike
than Gua became humanlike. He only learned a few simple words and often
took to making chimp howls when he wanted something. After only nine
months, the Kelloggs gave up on Gua, concerned that David would fail to
grow up like a normal human child. In the years since this project,
plenty of people have adopted chimps as babies, proving beyond a doubt
that the animals can never act completely human –even if they are
adorable in overalls.
According to Dalton's Atomic Theory, the <em>Law of Definite Proportion is applied when a compound is always made up by a fixed fraction of its individual elements.</em> This is manifested by the balancing of the reaction.
The reaction for this problem is:
H₂ + Cl₂ → 2 HCl
1 mol of H₂ is needed for every 1 mole of Cl₂. Assuming these are ideal gases, the moles is equal to the volume. So, if equal volumes of the reactants are available, they will produce twice the given volumes of HCl.
The answer is:
Sedimentary rock, metamorphic rock, and igneous rock.
<u>If you'd like to know why:</u>
Any type of rock can be a metamorphic rock. Metamorphic rocks are formed when a rock (any kind of rock) undergoes immense heat and pressure. If melting does not occur, it will become a metamorphic rock. If it melts, it becomes magma and from there, the magma, could eventually become an igneous rock and the rock cycle will start again.
Answer:
pH of the benzoic acid solution = 3.35
Explanation:
Benzoic acid is a weak monoprotic acid
pKa = 4.2
⇒ Ka = 6.3 x 10⁻⁵
C₆H₅COOH ⇄ C₆H₅COO⁻ + H⁺
Initial concentration C molar 0 0
At equilibrium (c - cα) cα cα
Acid dissociation constant Ka = 
⇒ 6.3 x 10⁻⁵ = α²c ................(1)
(for weak electrolyte 1 -α = 1)
Concentration of benzoic acid C = 25 x 0.126 x 10⁻³ = 0.00315 molar
From eqn (1)
α² = 
⇒ α = √( )
⇒ α = 0.14
So concentration of H⁺ ion = 0.14 x 0.00315 = 0.000441
pH = - log 0.000441 = 3.35
We not considered H⁺ concentration of water because pH < 7
