Here are the answers to your questions: 1. A) 6 bones There are 3 bones in each middle ear (malleus, incus, stapes), so a total of 6 bones in both middle ears. 2. Physics Question Step 1: Identify the given values and the unknown. The velocity of the stream, $v_s = 0.75 \text{ m/s}$. The angle of the resultant velocity with the stream direction, $\theta = 30^\circ$. We need to calculate the velocity of the boat relative to the water, $v_b$. Step 2: Relate the velocities using trigonometry. The boat heads perpendicular to the stream, so $v_b$ and $v_s$ are perpendicular. The resultant velocity $v_r$ forms the hypotenuse of a right-angled triangle. The angle $\theta$ is between $v_r$ and $v_s$. Therefore, we can use the tangent function: $$\tan(\theta) = \frac{\text{opposite}}{\text{adjacent}} = \frac{v_b}{v_s}$$ Step 3: Solve for $v_b$. $$v_b = v_s \tan(\theta)$$ $$v_b = 0.75 \text{ m/s} \times \tan(30^\circ)$$ $$v_b = 0.75 \text{ m/s} \times \frac{1}{\sqrt{3}}$$ $$v_b \approx 0.75 \text{ m/s} \times 0.57735$$ $$v_b \approx 0.433 \text{ m/s}$$ The velocity of the boat is $\boxed{\text{0.433 m/s}}$. 3. B. Cerebellum The cerebellum is responsible for coordinating voluntary movements, balance, and motor learning, such as riding a bicycle or driving a car. 4. B. increases the rate of change in concentrations of X, Y and Z A catalyst increases the rate of both the forward and reverse reactions equally, thereby increasing the rate at which equilibrium is reached. This means the concentrations of reactants and products change more quickly. 5. D. CH3CHO Incomplete oxidation of ethanol ($\text{CH}_3\text{CH}_2\text{OH}$) yields ethanal ($\text{CH}_3\text{CHO}$), which is an aldehyde. Complete oxidation would yield ethanoic acid ($\text{CH}_3\text{COOH}$). 6. B. begins and ends with capillaries The hepatic portal vein is unique because it carries blood from the capillary beds of the digestive organs (like the intestines) to the capillary beds (sinusoids) of the liver, rather than directly back to the heart. 7. B sp³ and s In methane ($\text{CH}_4$), the carbon atom undergoes $\text{sp}^3$ hybridization. Each of the four $\text{sp}^3$ hybrid orbitals of carbon overlaps with the $1\text{s}$ orbital of a hydrogen atom to form a C-H bond. 8. C. Distribution of bile Blood performs functions like maintenance of body temperature, formation of clots, and transportation of excretory materials. Bile is produced by the liver and transported through bile ducts to the small intestine; it is not distributed by the blood as one of its functions. 9. A. reduced to lactic acid During anaerobic respiration in skeletal muscles, pyruvic acid is reduced to lactic acid to regenerate $\text{NAD}^+$. 10. C. glucose The end product of the digestion of carbohydrates (polysaccharides and disaccharides) is glucose (monosaccharides), which can be absorbed into the bloodstream. 11. 4) Peptidoglycan The cell wall of prokaryotic cells (bacteria) is primarily made up of peptidoglycan. 12. Diverging lenses are always concave. Another name for a diverging lens is a concave lens. 13. In a step-down transformer, $\text{N}_p$ is expected to be B > Ns A step-down transformer reduces the voltage, which means the number of turns in the primary coil ($\text{N}_p$) must be greater than the number of turns in the secondary coil ($\text{N}_s$). That's 2 down. 3 left today — send the next one.