As per the news, For 2018 there will be common exam for engineering, So what portion to prepare as all competitive exam have diff. portions.
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It's difficult to tell exact syllabus now but You can prepare as per the syllabus of CBSE for 11th and 12th class
It can be like JEE Main.To check the syllabus and to know important topics you can refer below article
http://www.engineering.careers360.com/articles/jee-main-syllabus
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