Top answers

Why are drug trials needed?

To determine the side effects of taking the drug on humans, to test for toxicity, to determine the correct dosage needed, and to test the effectiveness (efficacy) of the drug.
DP
Answered by Devna P. • Biology tutor
4086 Views

How is crude oil separated into fractions?

Crude oil is seperated using a method called fractional distillation. The hydrocarbons that make up crude oil have different boiling points, so when the crude oil is heated, each compound evaporates at a dif...
DP
Answered by Devna P. • Chemistry tutor
14402 Views

what is the difference between indefinite and definite particles?

The definite particle in arabic includes the letters 'alif' and 'laam' at the beginning of the word, so pronounced as 'al'. The purpose is to render the noun on which it is pre-fixed to. Consequantly, it is ...
ZI
Answered by Zainab I. • Arabic tutor
9662 Views

What is the difference between a recessive and dominant allele?

Alleles are different versions of a gene . Every person has two alleles for each gene (one from either parent). For example, the gene which determines eye colour can either have an allele for brown eyes or a...
EJ
Answered by Elisha J. • Biology tutor
14862 Views

Why does the bromine become polarised in HBr during electrophilic addition

A C to C double bond has a high electron density. As the bromine gets close to the C=C bond the high electron density repels the electrons in the H-Br bond further towards the H making the H slightly negativ...
RC
Answered by Richard C. • Chemistry tutor
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