Divide the total number of books by the number of classes to find the remainder.

Which quadrilateral has the properties above?
Let's analyze the properties:

• Property (i) "Has two pairs of parallel sides" describes a parallelogram.
• Property (ii) "All sides are equal" narrows it down to a rhombus or a square.
• Property (iv) "Diagonals are perpendicular bisectors" is true for a rhombus and a square.
• Property (iii) "Some angles are equal" is true for both a rhombus (opposite angles are equal) and a square (all angles are equal). A square is a special type of rhombus where all angles are $90^\circ$. Since the properties do not explicitly state that all angles are $90^\circ$, but only "some angles are equal", the most general quadrilateral that fits all these properties is a rhombus. The correct option is B. $\boxed{\text{Rhombus}}$

13. In Mbagathi Hospital, a doctor used a syringe that was 0.00689cm. How many significant figures was the diameter of the syringe?
To count significant figures:

• Non-zero digits are always significant.
• Leading zeros (zeros before non-zero digits) are not significant. In 0.00689: The leading zeros (0.00) are not significant. The digits 6, 8, and 9 are non-zero, so they are significant. Therefore, there are 3 significant figures. The correct option is D. $\boxed{3}$

14. A drop of ink was recorded as 0.0000892ml at Kiama School laboratory. Express the drop of ink in standard form.
Standard form (scientific notation) is written as $a \times 10^b$, where $1 \le |a| < 10$ and $b$ is an integer.
To convert 0.0000892 to standard form, move the decimal point to the right until there is one non-zero digit before the decimal point.
$0.0000892 \rightarrow 8.92$
The decimal point was moved 5 places to the right, so the exponent $b$ is $-5$.

The correct option is A. $\boxed{8.92 \times 10^{-5}}$

15. Grade 7 learners where asked to study the figure below. What value did they get for the angle marked $x$?
The figure shows two intersecting straight lines.
The angle $150^\circ$ and the angle adjacent to it on the straight line form a linear pair, so their sum is $180^\circ$.
Let the adjacent angle be $y$.

Angle $x$ is vertically opposite to angle $y$. Vertically opposite angles are equal.

The correct option is D. $\boxed{30^\circ}$

16. The county government of Kisumu donated 14,568,139 mosquito nets to flood hit areas in Kano Plains. What is the number rounded off to the nearest tens of thousands?