No one here to reply to my query.
But i somehow figured that main problem is in this part of code in Marksheet.aspx.cs.

DataTable dt = new DataTable("Review");
            dt.Columns.Add("Q. No.", typeof(Int32));
            dt.Columns.Add("Question", typeof(string));
            dt.Columns.Add("Selected", typeof(string));
            dt.Columns.Add("Correct", typeof(string));
            dt.Columns.Add("Verdict", typeof(string));

            foreach (DataRow r in dtable.Rows)
            {
           
                DataRow dr = dt.NewRow();
                dr["Q. No."] = r["serial"];
                dr["Question"] = r["question"];

                if ((int)r[6] != -1)
                {
                    dr["Selected"] = r[(int)r[6] + 2];

                    Label5.Text = dt.Rows.Count.ToString(); // Added later on to check the no. of rows in DataTable
      /* At this point, the page show that the table has only 9 rows. */
                }
                else
                {
                    dr["Selected"] = "NA";
                }

                dr["Correct"] = r[(int)r[5] + 1];

                if (dr["Selected"] == dr["Correct"])
                {
                    dr["Verdict"] = "1 Mark";
                    marks++;
                }
                else dr["Verdict"] = "0 Marks";

                dt.Rows.Add(dr);
            }

Please guys..help me out.