D. ammonia, because the other three are the only three strong bases in the world (we do not need to memorize base dissociation constant for the test, we just need to know the three strong bases)

Explanation:

q u i z l e t

8 0

3 years ago

Which of the following sentences represents a physical change? sugar dissolves in coffee iron rusts gasoline burns in an engine

MAXImum [283]

<u><em>Answer:</em></u>

Physical changes example is sugar dissolves in coffee
Chemical changes examples are iron rusts, gasoline burns in an engine and a candle burns.

Explanation.

Physical changes depend on only physical state, not on composition, which can be separated by physical means while chemical changes depend on composition and only separated by chemical ways.
As in case of iron rusting, gasoline and candle burn are cases chemical changes bcz they convert into another substance whose composition is different from other as compare to sugar which has same composition in coffee ,only state is changed from solid to liquid.

6 0

3 years ago

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Which one of the following best represents the predicted approximate chemical shift and coupling for the hydrogen(s) indicated w

s2008m [1.1K]

Answer:

1.00 ppm, doublet

7 0

3 years ago

The most common source of copper (Cu) is the mineral chalcopyrite (CuFeS2). How many kilograms of chalcopyrite must be mined to

diamong [38]

Answer:

0.693kg of CuFeS2 is needed to produce 240 grams of Cu.

Explanation:

In 1 mole of CuFeS2 is associated 1 mole of Cu.

Molar mass of CuFeS2 = 183.5 g/mol

Molar mass of Cu = 63.5g/mol

No of moles of copper present in 240g of chalcopyrite = 240/63.5 = 3.779moles

we know

1 mole of Cu → 1 mole of CuFeS2

in 3.779 moles of Cu → 3.779 moles of CuFeS2

3.779 moles of CuFeS2 = 3.779 * 183.5 = 693.45grams

CuFeS2 in kg = 0.693kg

5 0

3 years ago