Questions

An atom is the smallest particle of a substance. Chemical substances are divided into two major groups. They are

1. Pure Substances (and)

2. Mixtures.

There are two types of pure substances that are Elements and Compounds.

Elements : An element is a substance that is made up of only one kind of atoms and cannot be broken down into simpler substances by chemical means. Metals and Non- metals come under elements.

Examples of elements are Iron, Silver, Gold, Mercury etc.

Compounds : A Compound is a substance that is formed when two or more elements combine chemically.

Examples of compounds are Water, Carbon dioxide, methane, vinegar etc.

Mixtures : A Mixture is formed when two or more substances mixed together but not chemically combined.

Example: Air.

11

Because, on preprocessing the expression becomes  a = ( 3 + 2 * 2 + 3),  as Ist preference is multiply & then addition, it evalvates as(3+ 2 * 3 +2) = (3+6+2)=11.

Pallava

Europe from Asia are separated by Ural mountains.

Amazon Rainforest Forests are located in South America.

Ascomycota is a division or phylum of the kingdom Fungi that, together with the Basidiomycota, form the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. 

Hence, Sac formation is a characteristic of the Ascomycota fungi.

Cobalt therapy or cobalt-60 therapy is the medical use of gamma rays from the radioisotope cobalt-60 to treat conditions such as cancer.

Cobalt 60 is a synthetic radioactive isotope of cobalt with a half-life of 5.2714 years. It is produced artificially in nuclear reactors.

Secondary succession means in an ecosystem renewal of itself after all or a portion has been destroyed.

After a forest fire, the whole forest had destroyed but after that again renewal of that forest is also an example of secondary succession.