Answer : Option B) All atoms of a single substance are identical.
Explanation : The scientist John Dalton proposed the atomic theory which had the postulates as follows.
i) All matter/substances consists of indivisible particles known as atoms.
ii) Atoms of the same element/substance are similar in mass,shape and size, but differ from the atoms of other elements.
iii) Atoms obey the law of conservation of energy which says atoms cannot be created or destroyed.
iv) Atoms of different elements may combine with each other in a fixed, simple, whole number ratios to form any compound atoms.
v) Atoms of same element can combine in ratio with more than one to form two or more compounds.
vi) The atom is considered to be the smallest unit of matter that can take part in a chemical reaction
The gases we create are adding to that blanket making sun light harder to escape,so the world heats up due to this addition to the layer
The proportion of long-tailed squirrels may have increased due to increased food availability.
The statement has it that the percentage of long tailed increased also that the long tailed are better at jumping and balancing on trees.
The first option could is tempting but saying decrease in trees would not likely support the argument.
The last option has more sound options as more food availability may lead to population increment
Hope it helps....
In a mixture, we can separate the elements or compounds inside easily by using physical methods, such as filtration, evaporation, distillation etc.
However, a compund is two or more elements chemically combined together, so we cannot separate them using physical methods, only with checmicals methods such as apply heat or electricity (electrolysis)