Q4. Assertion: synovial joints allow considerable movement. Reason: they have a fluid-filled synovial cavity between the articulating surfaces of the two bones. Are both true, and does the reason explain the assertion?
Both are true in NCERT’s account (page 227): a joint cavity permits the surfaces to move relative to one another. The actual direction and range also depend on bone shape, capsule and ligaments.
Q5. Name the joint between the carpals.
A gliding joint, a kind of synovial joint (NCERT page 227).
Q6. Which NCERT example of a cartilaginous joint permits limited movement?
The joint between adjacent vertebrae in the vertebral column (NCERT page 227). Beyond the NCERT text: these are the vertebral-body joints with discs; the facet joints are synovial (Wikipedia, “Facet joint”, facts in our words).