NAT being the entrance examination for admission to 11th for JEE and NEET aspirants, the syllabus includes your 10th subjects in Mathematics and Science. So you should concentrate on topics like:

Verbal and Non Verbal Series, Logical Sequence of words, Verbal and Non Verbal Analogy, Coding and Decoding, Arithmetical Reasoning, Alphabet Text, Puzzle Test, Mirror Images, Analytical Reasoning, Blood Relation, Dice and Cube, Grouping of Identical figures, Calendar, Logical Venn Diagrams, Clock, Verbal and Non Verbal Classification, Paper folding and paper cutting, Rank and Time Sequence, Figure Matrix and Data Sufficiency

Science: Motion, Force, Laws of Motion, Gravitation. Work and Energy, Sound, Electricity, Magnetic fields of Electricity, Sources of Energy, Light, Human Eye, Structure of Atom, Atoms and Molecules, Chemical Reactions and Equations, Acid Base and Salts, Metals and Non metals, Carbon and its Compounds, Periodic Classification of Elements.

Mathematics: Real Numbers, Rational Numbers, Number System, Profit and loss, Percentage, Polynomials, Linear Equation in two variables, Lines and Angles, Triangles, Quadrilaterals, Parallelograms, Triangles, Circles, Area related to circles, Heron'd formula, Surface areas, Volumes, Statistics, Quadratic Equations, Arithmetic Progressions, Trigonometry, Coordinate Geometry, Probability.