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Chlorine, Cl, and Florine, F are both in group 7 of the periodic table so they have 7 electrons in the outer energy level, called valence electrons. Each fluorine atom makes one covalent bond to the chlorine...

This is a handy trick for quadratic equations ax^2 + bx + c = 0. e.g. (x^2 + 5x + 6). So a = 1, b = 5 and c = 6. To complete the square, let x^2 + 5x + 6 = 0. Then, take 6 to the other side to get x^2 + 5x =...

You usually know that a verb is in the second group when it finishes by "-ir". However, some verbs of the third group also end by "-ir". The differentiation is then possible when you look...

There is an easy way of knowing the difference between and when to use which object pronoun! To figure out the direct object of a sentence, simply ask yourself "who?" or "what?". For exam...

When dealing with essays under exam conditions, you need to be able to quickly work out what is being asked and what you should include. It is often helpful to go through the question and pick out the key wo...